On Tuesday, Washington Metro Area Transit Authority spokeswoman Candace Smith said five more bodies were recovered Tuesday from the crash site near the Maryland border after four bodies were recovered from the wreckage Monday after the rush-hour crash.
Listen to Kwame Holman's report on the investigation for Tuesday's NewsHour:
Two men and seven women were killed including Jeanice McMillan, the operator of the train that barreled into and on top of a stopped train, Smith said. All the victims were adults. More than 70 riders were taken to the hospital as well.
Federal officials investigating the crash said a 2006 warning for the transit authority to upgrade or retire older, less protected subway cars, some of which were involved in Monday's wreck, had gone unheeded.
"We recommended to WMATA to either retrofit those cars or phase them out of the fleet. They have not been able to do that and our recommendation was not addressed," National Transportation Safety Board spokeswoman Debbie Hersman said at a news conference at the scene.
NTSB had urged the Metro system to replace its older subway cars or upgrade their crashworthiness following a 2004 accident that injured 20 passengers, federal records show.
The crash occurred on Washington's busiest subway line about 5 p.m., on the city's northeastern outskirts on a relatively lengthy stretch of track where trains can build up considerable speed.
Both trains were heading south into the city as rush hour commuters were headed out of the city. The lead train was stopped because another train was ahead of it.
It was unclear why the following train had not received the signal to stop as well, or why the operator did not stop her train manually when she saw the tracks blocked ahead of her, officials said.
Hersman said investigators expect to recover recorders from the train that was struck. The train that triggered the collision was part of an old fleet that was not equipped with the devices, which can provide valuable information to determine why the crash occurred, Hersman said.
Passenger Maya Maroto, 31, was riding on McMillan's train. "We were going full speed -- I didn't hear any braking. Everything was just going normally. Then there was a very loud impact. We all fell out of our seats. Then the train filled up with smoke. I was coughing," Maroto said.
Maroto, of Burtonsville, Md., said there was confusion after the impact because no announcements were immediately made. She said some passengers wanted to climb out, but others were afraid of being electrocuted by the electrified third rail.
The impact was so powerful that the striking train was compressed to about a third of its original size, Mayor Adrian M. Fenty said. The floor of the train disappeared below the feet of the horrified passengers. Several of the dead were crushed, their bodies not located until a crane removed part of the striking train on Tuesday. Firefighters had to use heavy rescue equipment to cut open the cars to reach survivors trapped inside.
Rescue crews used thermal imaging and cadaver dogs to help find bodies. D.C. Fire Chief Dennis L. Rubin said the wooded areas on both sides of the tracks had been searched for survivors or dead.
The identities of the dead are still being confirmed, after which their relatives will be notified, D.C. Police Chief Cathy L. Lanier said. Their names will not be released until that process is completed, she said, according to the Washington Post.
The only other Metro subway system crash involving passenger fatalities occurred Jan. 13, 1982, when three people died as a result of a derailment. That was a day of disaster in the capital: shortly before the subway crash, a plane slammed into the 14th Street Bridge immediately after takeoff from Washington National Airport. The plane crash, during a severe snowstorm, killed 78 people.
In 2007, a subway train derailed in downtown Washington, sending 20 people to the hospital and prompting the rescue of 60 others from the tunnel. In November 2006, two Metro track workers were struck and killed by an out-of-service train. An investigation found that the train operator failed to follow safety procedures. Another Metro worker was struck and killed in May 2006.
The subway had a total of 215.3 million trips in the last fiscal year.