
Photo taken on May 18, 2013 shows the scene of a Metro North train collision in Fairfield, Connecticut, the United States. Investigators have begun their probe into the commuter train collision which took place in the US state of Connecticut during Friday evening rush hour, leaving more than 70 injuries, government officials said in a press briefing Saturday. (Xinhua/Wang Lei)

Photo taken on May 18, 2013 shows the scene of a Metro North train collision in Fairfield, Connecticut, the United States. Investigators have begun their probe into the commuter train collision which took place in the US state of Connecticut during Friday evening rush hour, leaving more than 70 injuries, government officials said in a press briefing Saturday. (Xinhua/Wang Lei)

A policeman works at the site of a Metro North train collision in Fairfield, Connecticut, the United States, on May 18, 2013. Investigators have begun their probe into the commuter train collision which took place in the US state of Connecticut during Friday evening rush hour, leaving more than 70 injuries, government officials said in a press briefing Saturday. (Xinhua/Wang Lei)

Photo taken on May 18, 2013 shows the scene of a Metro North train collision in Fairfield, Connecticut, the United States. Investigators have begun their probe into the commuter train collision which took place in the US state of Connecticut during Friday evening rush hour, leaving more than 70 injuries, government officials said in a press briefing Saturday. (Xinhua/Wang Lei)

Investigators from the National Transportation Safety Board (NTSB) attend a press briefing following a Metro North train collision in Fairfield, Connecticut, the United States, on May 18, 2013. Investigators have begun their probe into the commuter train collision which took place in the US state of Connecticut during Friday evening rush hour, leaving more than 70 injuries, government officials said in a press briefing Saturday. (Xinhua/Wang Lei)

Photo taken on May 18, 2013 shows the scene of a Metro North train collision in Fairfield, Connecticut, the United States. Investigators have begun their probe into the commuter train collision which took place in the US state of Connecticut during Friday evening rush hour, leaving more than 70 injuries, government officials said in a press briefing Saturday. (Xinhua/Wang Lei)

Connecticut Gov. Dan Malloy (1st R) speaks at a press briefing following a Metro North train collision in Fairfield, Connecticut, the United States, on May 18, 2013. Investigators have begun their probe into the commuter train collision which took place in the US state of Connecticut during Friday evening rush hour, leaving more than 70 injuries, government officials said in a press briefing Saturday. (Xinhua/Wang Lei)

A policeman works at the site of a Metro North train collision in Fairfield, Connecticut, the United States, on May 18, 2013. Investigators have begun their probe into the commuter train collision which took place in the US state of Connecticut during Friday evening rush hour, leaving more than 70 injuries, government officials said in a press briefing Saturday. (Xinhua/Wang Lei)

A policeman works at the site of a Metro North train collision in Fairfield, Connecticut, the United States, on May 18, 2013. Investigators have begun their probe into the commuter train collision which took place in the US state of Connecticut during Friday evening rush hour, leaving more than 70 injuries, government officials said in a press briefing Saturday. (Xinhua/Wang Lei)

Photo taken on May 18, 2013 shows the scene of a Metro North train collision in Fairfield, Connecticut, the United States. Investigators have begun their probe into the commuter train collision which took place in the US state of Connecticut during Friday evening rush hour, leaving more than 70 injuries, government officials said in a press briefing Saturday. (Xinhua/Wang Lei)

Photo taken on May 18, 2013 shows the scene of a Metro North train collision in Fairfield, Connecticut, the United States. Investigators have begun their probe into the commuter train collision which took place in the US state of Connecticut during Friday evening rush hour, leaving more than 70 injuries, government officials said in a press briefing Saturday. (Xinhua/Wang Lei)