Officials in the Pittsburgh and Johnstown metro areas knew United Airlines Flight 93 was heading their way, but didn't know where it was for 10 minutes.

Pittsburgh Mayor Tom Murphy was on the phone with officials from the FBI and the Federal Aviation Administration, who could only say the plane was heading east from Ohio.

"They had the jet coming out of Cleveland and losing it when it came into Pittsburgh airspace. There was no communication with it, and we were concerned," Murphy said.

Cleveland air traffic controllers called John P. Murtha Johnstown-Cambria County Airport to alert them about the situation. Air traffic manager Dennis Fritz was told that a large aircraft 20 miles south of the airport was bearing down on the facility, which does not have a radar system.

Air traffic managers in the airport's tower began scanning the horizon for the Boeing 757 that had taken off from Newark International airport about two hours earlier carrying 38 passengers, two pilots and five flight attendants.

"It was an aircraft doing some unusual maneuvers at a low level, which is unusual for an aircraft that size," Fritz said.

Seeing nothing, air control tower workers began to think the aircraft was flying below the 2,800-foot-high ridges in the Allegheny front.

The plane veered south somewhere within 15 miles of Johnstown, Fritz said.

A witness on the ground called the Westmoreland County 911 center to report a large aircraft flying low and banking from side to side.

Around 10 a.m., the plane slammed nose-first into the ground and exploded over an abandoned strip mine.

Witnesses who arrived shortly afterward said only small pieces of the aircraft remained.

"There was a crater in the ground that was really burning," said Eric Peterson, 20, who was working in his nearby shop when the United Airlines jet passed low overhead.

Peterson said he saw no bodies at the scene, but saw no signs of life, either.