Residents of North Texas said they saw flames and heard a window-rattling boom Saturday about the time the space shuttle Columbia apparently disintegrated on its way to a scheduled landing at Cape Canaveral.

"It was like a car hitting the house or an explosion. It shook that much," said John Ferolito, 60, of Carrolton, north of Dallas.

NASA declared an emergency after losing communication with Columbia as the ship soared across Texas at an altitude of about 200,000 feet while traveling at six times the speed of sound. The space agency said search and rescue teams in the Dallas-Fort Worth area were alerted.

Helen Watts with the Dallas Fire Department said search and rescue teams were on standby but had not been dispatched to any locations.

Gary Hunziker in Plano said he saw the shuttle flying overhead.

"I could see two bright objects flying off each side of it," he told The Associated Press. "I just assumed they were chase jets."

"I was getting read to go out, and I heard a big bang and the windows shook in the house," Ferolito told The AP. "I was getting ready to go out and I heard a big bang and the windows shook in the house. I thought it was a sonic boom."

Louisiana State Police in Bossier City, 182 miles east of Dallas, got so many calls that one trooper had to be assigned just to answer the phone.

"One said he saw a plane breaking up over Shreveport. One said he saw a big ball of fire. One guy said his house had a blast that shook his house," state police Sgt. Steve Robinson said. That call was from DeSoto Parish, south of the parish where Bossier City is located.

North of Dallas, Chris Linville stopped working at Brookhaven Pet Hospital in Addison to go outside and watch the shuttle pass overhead.

"From the viewpoint we had, we did see some flames. We thought maybe it was from the engines or something we didn't know," said Linville, 21. "We knew it was flying over, and we were actually looking for the shuttle passing by. We had no idea."