LOS ANGELES (AP) _ A TWA airliner with 162 people aboard was evacuated Monday when a ventilation duct ruptured, spewing dust into the jet's cabin as it prepared for takeoff. Some passengers thought a bomb had gone off.

The 153 passengers slid down the Boeing 767's emergency chutes, but there were no injuries, said fire department spokesman Jim Wells.

``A fellow came running from the back yelling something about a bomb,'' said passenger Barry Fernando.

``Everyone just started running toward the front. And I think the stewardess was telling us to stay put but the guy in front of us popped the emergency exit and we went out,'' passenger Mary Ann Khalil told KABC-TV.

There was no immediate explanation of why the duct ruptured aboard the jet, which carried a crew of nine. There was no fire, said TWA spokesman John McDonald in St. Louis.

TWA Flight 22 was taxiing for a 12:30 departure from Los Angeles International Airport to New York when the pilot reported smoke in the cockpit and announced the evacuation, said Mitch Barker, a Federal Aviation Administration spokesman in Seattle.

Passengers were given seats on other TWA flights or other airlines, or had the option of waiting for a Tuesday flight, McDonald said.