All of the deaths were caused by a tornado that struck the northwest Oklahoma town of Woodward Sunday.
The man, whose name was not released, was transported by helicopter to a hospital in Amarillo, Texas, along with his critically injured wife, The (Oklahoma City) Oklahoman reported.
The man died Sunday night and his wife remained in critical condition, Matt Lehenbauer, Woodward emergency management director, said Monday.
The bodies of Frank Hobbie and his daughters, ages 5 and 7, were found Sunday at the Hidden Valley Mobile Home Park in Woodward, where 89 homes and 13 businesses were destroyed.
Amy Elliot of the Oklahoma Medical Examiner's Office said the other two people killed, a man identified as Derrin Juul and a 10-year-old girl presumed to be his daughter, were in a car sent rolling by the tornado, CNN reported.
The network reported the twister that struck Woodward was one of about 130 believed to have been created by a massive storm system that hit 10 Midwest and Plains states. At least 29 other people were injured.
It wasn't until Monday morning that the National Weather Service lifted the last tornado watches in Minnesota, Wisconsin, Arkansas, Iowa and Illinois.
Oklahoma Gov. Mary Fallin, who declared a state of emergency in a dozen counties, said the number of casualties could have been worse.
"It's remarkable that we didn't have more loss of life in Woodward," she said Sunday.
In Wichita, work at Spirit AeroSystems and Boeing buildings was suspended temporarily because of damage reported from Saturday night's tornadoes, The Wichita Eagle reported.
Spirit will be closed at least through Tuesday, spokeswoman Debbie Gann said Sunday, adding damage was "substantial" in some buildings.
"Our priority is to get in and do a damage assessment," Gann said.
At Boeing, spokeswoman Yvonne Johnson-Jones said several buildings at the plant sustained damage, but she was unable to provide specifics, adding that Boeing has suspended operations through Monday due to the power outage in the area.
Two QuikTrip stores and a Hawker Beechcraft plant were also damaged during the storm.
Officials in Iowa said the town of Thurman was pounded.
"About 75 percent of the homes are damaged or destroyed," said Mike Crecelius, Fremont County's emergency management director.
Four truckers were hurt when their rigs were hurtled off Interstate 29 by a tornado that hit Thurman.
In Creston, Iowa, a confirmed twister hit a hospital, blowing out windows and damaging the roof, but no major injuries were reported. The patients were sent to other hospitals.
In northeastern Minnesota, residents awoke Monday to a blanket of snow and schoolchildren got a rare snow-day in April.
The area received 4-9 inches of snow and was under a winter storm warning.