WASHINGTON (AP) -- An empty subway train rolled backward into a train full of passengers near the National Zoo on Wednesday, injuring at least 20 people, transit officials said.
The second train, carrying about 70 passengers, had pulled into one of the city's busiest stations moments before the empty train backed into it. Most of the 75-foot-long rear car of the empty train came off the tracks and about one-third of its aluminum shell was pulled apart.
The crash sounded ``like nothing you ever heard, like thunder,'' said Calvert Sawyers, 58, the train operator.
Witnesses said the operator began screaming for people to get off the occupied train a few seconds before the impact.
``The next thing we knew there was a big crash, and a lot of dirt and dust flying everywhere, and panic, and everybody just ran out of the Metro station,'' said Mike Cucciardl, a teacher traveling on the train with more than 40 kids from a District of Columbia charter school. Thirteen students were among the injured.
None of the injuries was life-threatening, said Alan Etter, a fire department spokesman. He said it's ``astounding,'' given the force of the crash, that more people weren't more seriously hurt. The worst injury appeared to be a broken leg, he said.
The crash happened after a loaded six-car train pulled into the Woodley Park-National Zoo Metro station around 12:49 p.m., Metro spokesman Steven Taubenkibel said.
Each train has an automatic control system to keep trains a safe distance apart, Deputy General Manager for Operations James Gallagher said. Officials were looking into whether the system failed.
``The train rolled backward. Trains don't roll backward,'' he said. ``There's something unusual about this event.''
Train operators can manually override the automatic braking system, but officials said that would require permission from the operations control center.
Officials said they were questioning the two drivers and examining mechanical records. Damage was estimated at $1.5 million. Officials didn't believe the crash was related to terrorism.
Metro was calling Sawyers a life saver for ordering the passengers off the train.
Sawyers said there were only seconds to react. ``I looked up and saw a train coming backwards down the track,'' he told WJLA television. ``I just called out to the people to get off the train.''
The National Transportation Safety Board took control of the scene late Wednesday afternoon. Metro officials said the trains won't be moved until the NTSB completes its probe.
Investigators said Wednesday night that they would look at the age of the trains, their braking systems, maintenance records and the possibility of operator error. Neither train had an event recorder, or ``black box,'' an NTSB spokesman said. However investigators were hoping to get information about the crash from station surveillance video.
The subway system's last serious crash was in January 1996. An operator was killed after his train slid past an outdoor platform and collided with an out-of-service train during a winter snowstorm.
The Woodley Park station would reopen for the Thursday morning rush hour, Metro officials said, although trains would share a single track.
The transit system planned to run eight-car trains instead of the usual six-car trains, and offer free bus service along the route. Riders who use the Red Line during the morning and afternoon rush hours would pay the reduced, non-rush hour fare, Metro officials said.