SHANKSVILLE, Pa. (AP)- A United Airlines jetliner crashed Tuesday morning in western Pennsylvania, the airline said. Minutes earlier, a man who said he was a passenger on the plane told an emergency dispatcher in a cell phone call: ``We are being hijacked, we are being hijacked!`` United said 45 people were aboard Flight 93 from Newark, N.J., to San Francisco. The fate of the passengers was not immediately announced. The Boeing 757 crashed north of Somerset County airport, about 80 miles southeast of Pittsburgh. The crash was one of four reported Tuesday by United and American Airlines. United said a second jet crashed at an undisclosed location. American Airlines initially said two of its planes crashed into the World Trade Center in New York but later said that was unconfirmed. In Pennsylvania, an emergency dispatcher received a cell phone call at 9:58 a.m. from a man who said he was a passenger locked in a bathroom aboard United Flight 93, said dispatch supervisor Glenn Cramer in neighboring Westmoreland County. The man repeatedly told officials the call was not a hoax. ``We are being hijacked, we are being hijacked!`` Cramer quoted the man from a transcript of the call. The man told dispatchers the plane ``was going down. He heard some sort of explosion and saw white smoke coming from the plane and we lost contact with him,`` Cramer said. According to Somerset County dispatchers, Flight 93 crashed about 10 a.m. about 8 miles east of Jennerstown. ``It shook the whole station,`` said Bruce Grine, owner of Grine`s Service Center in Shanksville, about 2 1/2 miles from the crash. ``Everybody ran outside, and by that time the fire whistle was blowing.`` Michael R. Merringer was out on a mountain bike ride with his wife, Amy, about two miles away from the crash site. ``I heard the engine gun two different times and then I heard a loud bang and the windows of the houses all around rattled,`` Merringer said. ``I looked up and I saw the smoke coming up.`` The couple rushed home and drove near the scene. ``Everything was on fire and there was trees knocked down and there was a big hole in the ground,`` he said. United said Flight 93 left Newark, N.J., at 8:01 a.m. with 38 passengers, two pilots and five flight attendants. In Chicago, United CEO James Goodwin said the airline is working with authorities including the FBI. United said it was sending a team to Pennsylvania to assist in the investigation and to provide assistance to family members. ``Today`s events are a tragedy and our prayers are with everyone at this time,`` Goodwin said. After the crashes the three passenger terminals at Newark International Airport were evacuated. At 11:30 a.m., several hundred people were still clustered at the Terminal A baggage carousel, while shotgun-toting officers patrolled. Ticket counters were deserted. Because of the attacks in New York, the Federal Aviation Administration had ordered all departing flights canceled nationwide, and any planes already in the air were to land a the nearest airport. The Pennsylvania crash came after the order was issued.