AP Photo

The Bretigny-sur-Orge train station, south of Paris, is seen Friday after a packed passenger train derailed, killing at least six people.. (July 13, 2013)

BRETIGNY-SUR-ORGE, France - A train carrying hundreds of passengers derailed and crashed into a station outside Paris on Friday on one of the busiest days of the year for vacation getaways. At least six people were killed and dozens were injured, officials said.

The crash was the deadliest in France in several years. French President Francois Hollande rushed to the scene at the Bretigny-sur-Orge station, 12 miles south of Paris. The Interior Ministry said some 192 people were either injured or being treated for shock -- of which nine were in critical condition.

Four of the seven train cars slid toward the station, crushing part of the metallic roof over the platform. Images on French television and on Twitter showed gnarled metal and shards on the platform, and debris from the crash clogging the stairwell leading beneath the platform.

Some 300 firefighters, 20 medical teams and eight helicopters were deployed to get survivors out of the metal wreckage, according to the Interior Ministry.

The accident came as France is preparing to celebrate its most important national holiday, Bastille Day, on Sunday, and as masses of vacationers are heading out of Paris and other big cities to see family or for summer vacation.

Hollande said an inquiry has been launched to determine the cause of the accident.

"The inquiries will be public so that there is absolutely no doubt on what happened," he added.

Witnesses reported that the train was not moving at an excessive speed, deepening the mystery of what happened.

Ben Khelifa, a 20-year-old accounting apprentice whose commuter train was on the adjacent track, told The Associated Press that the derailed train "was unrecognizable."

"There was nothing but metal scraps," he said. "The train just collapsed, just like that, on its side. ... There was blood."

He added that he was one of a number of passengers in the adjacent train that went to help pull trapped survivors out of the wreckage. "People were screaming, people were asking where their children were," he said.

Another witness, Bazgua El Mehdi, 19, told Le Parisien newspaper: "I heard a loud noise. A cloud of sand covered everything. Then the dust dissipated. I thought it was a freight train, but then we saw the first casualties ... Many passengers on the (train) were crying."

It was unclear whether all the casualties were inside the train, or whether some had been on the platform, or how fast the train was traveling. The head of the SNCF rail authority, Guillaume Pepy, called it a "catastrophe."

The train's third and fourth cars initially derailed, which then knocked the other cars off the track, Pepy said. "Some cars simply derailed, others are leaning, others fell over," he said.

© 2013 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.