From President Reagan to school children to workers who made parts for the space shuttle Challenger, Americans mourned the six astronauts and teacher Christa McAuliffe who perished when the shuttle exploded moments after takeoff.
In what may have been the most horrifying live television since Jack Ruby shot Lee Harvey Oswald in 1963, viewers watched Tuesday as Challenger exploded into a fiery ball and plummetted to the sea in pieces, leaving trails of white smoke in the sky.
While NASA organized an investigative team to determine the disaster's cause, people everywhere were stunned over the deaths of their modern-day heroes in the worst accident ever suffered by the space program.
President Reagan ordered flags flown at half-staff on all federal buildings, military installations, naval ships and embassies for one week ''as a mark of respect to the memory'' of the seven Challenger astronauts.
''Nancy and I are pained to the core over the tragedy of the shuttle Challenger,'' Reagan said in televised address, calling the accident ''truly a national loss.''
At NASA's Washington headquarters, employees sat stunned in an auditorium monitoring network coverage of the Shuttle explosion.
''It was a big shock to all of us,'' said Orlando Gutierre, NASA's Hispanic program manager.
''These astronauts are the cream of America. If you look around this room, you see all these people -- not sadness showing, but complete disbelief. They still can't believe it.''
The New York Stock Exchange was to observe one minute of silence at 11 a.m. today to honor Challenger's crew and the traditional tower lights of the Empire State Building were turned off Tuesday night in memory of the seven.
The disaster was particularly horrifying for the many students watching the liftoff.
Third and fourth graders at Rockford Elementary School in Rockford, Minn., thought the crew could eject from the shuttle and became dismayed when told that kind of escape was not possible, said principal Robert Ziegler.
At P.S. 183 in New York City, school officials decided news of the tragedy could not be trusted to a public address system.
Barbara Schneider, science coordinator at the school, said, ''We went from class to class with the sad news.''
At Washington Elementary School in Omaha, Neb., 20 deaf kindergarten and first-grade pupils were watching the space shuttle launch. Teacher Sue Craik stood by the set to translate the broadcast reports into sign language. As the television reported the shuttle's explosion, Cralik continued to sign news reports to the stunned students.