Sandy was downgraded to a post-tropical cyclone shortly after landfall but was still kicking up strong winds blamed for a partial crane toppling near Carnegie Hall in New York, while driving rain and pounding surf inundated near-vacant cities in the Mid-Atlantic states. The storm made landfall at about 6 p.m., CBS-TV, Philadelphia, reported.
The National Hurricane Center in Miami warned Sandy is "expected to bring life-threatening storm surge and coastal hurricane winds plus heavy Appalachian snows," with one official calling it the "worst-case scenario."
Two U.S. deaths were attributed to Sandy, a man killed when a tree hit his home in New York City's Queens borough, and a person killed in a storm-caused car crash in Maryland, Fox News reported.
The facade of a building in New York's Chelsea neighborhood collapsed, sending debris raining onto 8th Avenue.
New York Mayor Michael Bloomberg held a 10 p.m. news conference to urge residents not to call 911 unless it is truly a "life-threatening emergency." He said 911 was receiving 10,000 calls every 30 minutes, roughly 10 times the normal rate. He also admonished drivers to stay off the roads, saying stuck vehicles are complicating things for emergency responders.
"We need to keep the roads clear," Bloomberg said. "Do not drive."
The mayor said he expects the storm surge to recede by midnight but said "the time to leave has passed," adding, "Do not go outside, it is very dangerous. ... You have to stay wherever you are."
Bloomberg said backup power New York University's hospital had stopped working and the city was working to help move people out. He also noted a "large number of fires" have been caused by downed wires and electrical problems.
A 63-mile stretch of New Jersey's Garden State Parkway was closed because of flooding.
With massive power outages throughout the region, travel plans were on hold, schools were canceled and government offices were shuttered. The storm is expected to affect as many as 60 million people.
Sandy still had maximum hurricane-force winds of 75 mph, moving northwest at 18 mph, the hurricane center said in its 11 p.m. EDT advisory. The storm was centered 10 miles southwest of Philadelphia.
Floodwaters forced the Port Authority of New York and New Jersey to close New York's LaGuardia Airport, NY1 News reported. Power was out in parts of Lower Manhattan, where the water level at Battery Park reached a record 11.25 feet.
Maryland Gov. Martin O'Malley told MSNBC Sandy was to blame for at least one fatality in Montgomery County in which a car hydroplaned and crashed. He also said Maryland would add an additional day of early voting Friday.
New Jersey Gov. Chris Christie said some people had decided to stay in Atlantic City despite his urging them to evacuate, and he laid the responsibility on Mayor Lorenzo Langford, WPIV-TV, Philadelphia, reported.
"So for those of you who are on the barrier islands who decided it was a better idea to wait this out than to evacuate and for those elected officials who decided to ignore my admonition, this is now your responsibility," Christie said.
He said no further evacuation efforts would be undertaken because of the danger.
Rescue operations, he said, "are putting first responders in significant, significant danger and it's not fair to their families to be putting them in danger because you decided to be hardheaded."
Forecasters said Sandy, already responsible for at least 67 deaths in the Caribbean, was likely to collide with a cold front, spawning a superstorm capable of generating flash floods, snowstorms and massive power outages.
President Obama said he spoke with governors of a number of states in Hurricane Sandy's wide, wide path along the eastern seaboard from North Carolina to the New England states. Even Florida was affected Monday by dangerous surf generated by Sandy.
"They have issues emergency declarations. Those have been turned around quickly here in the White House," Obama said. "We have prepositioned assets so that FEMA [Federal Emergency Management Agency] personnel are working closely with state and local governments. We're making sure that food and water and emergency generation is available for those communities that are going to be hardest hit."
In New York, authorities said they're concerned that the partial collapse of a crane could plunge onto the street, WABC-TV, New York, said.
Sandy forced construction work to be suspended, so it was unclear whether anyone was at the job site at one what WABC said is one of the tallest towers in Manhattan.
Meanwhile, Mayor Michael Bloomberg announced that New York City schools would be closed Tuesday. Classes were canceled in several cities for about 2 million students.
The New York Stock Exchange posted on its website it would be closed for a second straight day Tuesday.
"In consultation with other exchanges and market participants, NYSE ... will close its markets in coordination with all U.S. equities, bonds, options and derivatives markets on Tuesday," the statement said. "We intend to re-open our U.S. markets on Wednesday, Oct. 31, 2012, conditions permitting."
The Office of Personnel Management said on its website that federal offices in Washington would be closed to the public for a second day Tuesday.
WABC said the Brooklyn Battery and Holland tunnels were closed, and that speeds were reduced on the George Washington Bridge and three Staten Island crossings.
Amtrak said its Northeast Corridor services were canceled through Tuesday because of Sandy. Airports reported thousands of flights had been canceled.
Obama said his team knows "this is going to be a slow-moving process through a wide swath of the country, and millions of people are going to be affected."
"So the most important message that I have for the public right now is, please listen to what your state and local officials are saying. When they tell you to evacuate, you need to evacuate," Obama said. "Do not delay, don't pause, don't question the instructions that are being given because this is a serious storm and it could potentially have fatal consequence[s] if people haven't acted quickly."
"But keep in mind that for folks who are not following instructions, if you are not evacuating when you've been asked to evacuate, you're putting first responders at danger," Obama said, a sentiment echoed by FEMA Administrator Craig Fugate.
Fugate said one of his key concerns was "people who didn't evacuate" but later needed to be rescued, putting responders "in harm's way."
Obama said he wasn't worried about Sandy's impact on the election.
"I'm worried about the impact on families, and I'm worried about the impact on our first responders. I'm worried about the impact on our economy and on transportation," he said. "The election will take care of itself next week."
Hurricane Center Director Rick Knabb said Sandy would be a "long-duration" event.
"Time has run out, or is running out, for preparations," Knabb said.
Hurricane-force and tropical storm-force gusts could last in some areas "into Tuesday night or Wednesday morning." Forecasters also warned winds would be much higher at the upper floors of high-rise buildings than at ground level.
Rainfall in some areas could be "measured in feet," not inches, Knabb said, while 2-3 feet of snow could fall in the mountainous regions of West Virginia.
Republican presidential candidate Mitt Romney on his website said he and his wife were keeping those in Sandy's path in their prayers.
"I hope that if you can, you'll reach out to your neighbors who may need help getting ready for the storm -- especially your elderly neighbors," he said in the post. "And if you can give of your resources or time, please consider supporting your local Red Cross organization."
Off the coast of Cape Hatteras, N.C., the U.S. Coast Guard reported rescuing 14 of 16 people from the replica tall ship HMS Bounty, which was built for the 1962 movie "Mutiny on the Bounty" and also used in "Pirates of the Caribbean," who were in life rafts. CNN later reported one of the two missing people had been recovered, but was characterized as unresponsive and the 16th person was still missing.
The Coast Guard said in a release the 16 Bounty crew members had abandoned ship after it lost power 90 miles from Cape Hatteras and began taking on water. It originally reported 17 people were on board the vessel, which sank.
Weather advisories were posted along the Eastern Seaboard and inland into West Virginia, western Virginia, Kentucky and western Maryland.
Rain and tropical storm-force winds were reported in Atlantic City, where casinos were closed Sunday after Gov. Chris Christie declared a state of emergency.
By 7:30 a.m., streets near the new Revel casino resort were flooded with more than a foot of water, witnesses told The (Newark) Star-Ledger.
On its forecast track, the center of Sandy was expected to make landfall along or just south of the southern New Jersey coast Monday evening or night. Hurricane-force winds extended outward from center as far as 175 miles while tropical storm-force winds extended as far as 485 miles.
"It could be bad," Coast Guard Rear Adm. Steven Rattior told CNN, "or it could be devastation."
Storm-surge and high tide could raise water levels anywhere from 1-to-11 feet above normal along the East Coast to the Canadian border.
The United Nations canceled all meetings at its New York headquarters. Broadway shows were canceled, as were performances at New York's Carnegie Hall and the Metropolitan Opera.
Early voting was canceled in several states. Virginia's governor said Sunday his state would take measures to ensure residents could vote, despite potential hurdles created by the storm.
A UPI-CVoter poll indicated 1 percent of the 1,585 adults polled last week before the threat of Sandy became imminent said natural disasters were the top issue facing the country, compared with 5 percent who cited healthcare and 3 percent who named the war on terror. Pollsters said the issue was expected to grow in importance in advance of the Nov. 6 balloting since Sandy is on track to devastate several swing states.