NEWTON, Mass. (AP) – Two above-ground trains derailed after a rear-end collision near a mass transit station in suburban Boston, injuring several passengers and killing the operator of one of the trains.

A firefighter on the scene told The Associated Press that the operator’s body was still in the wreckage late Wednesday.

Terry Jones told The Boston Globe that the operator was his 24-year-old daughter, Terrese Edmonds.

She was in the train that hit another on the city’s “T” system in suburban Newton. Investigators did not know what caused the wreck.

The accident occurred shortly before 6 p.m. Wednesday near the Woodland Station in Newton, said Joe Pesaturo, a spokesman for the Massachusetts Bay Transportation Authority. He said a 2-car outbound Green Line trolley slammed into the rear of another 2-car train that was approaching the station.

“The first one was stopped at a red signal and was ready to proceed to the station when it was struck,” he said.

Pesaturo said one passenger was flown by medical helicopter to a Boston hospital after the accident and others were taken to nearby Newton-Wellesley Hospital.

A spokesman for the hospital said eight patients were brought in for treatment, including six who were rushed in by ambulance. None had suffered serious injuries, Brian O’Dea said.

The National Transportation Safety Board was sending a team of 10 investigators, who were expected begin arriving at the crash scene Wednesday night to review the site and interview witnesses, spokesman Peter Knudson said.

The investigators will then travel to Washington where they “will continue to look at a lot of factual information about the train system, operators, human factors, signal, maintenance issues,” Knudson said.

The board investigates about a dozen train crashes a year, focusing on those that have significant safety issues that the board believes can effectively address through recommendations, he said.

Passengers and witnesses described a chaotic and frightening scene.

“There was two separate impacts: the first knocked me off my seat, the next knocked me across the aisle,” said Matt Stone, 46, an accounting manager from Framingham, who was aboard the train that was slammed from behind.

“There was a 70-year-old old guy who went ballistic screaming at the conductor: ‘You killed my wife! You killed my wife!’ And the wife is going, ‘I’m OK! I’m OK,”‘ Stone told The Boston Globe. Most of the 20 to 25 people on his train were not seriously injured, but a few appeared to be badly hurt, he said.

Frank Lam said a few people were thrown around during the impact, but most were able to walk off the train.

The 41-year-old Natick resident said he saw a woman who operated one of the trains trapped into one corner of a trolley. The woman was conscious. “All I saw was a T blue shirt. It looked like her back or something,” he told the Globe.

“I was getting out of the car on the way home from school and I was going into the house when I heard a really long, loud crash, like a rumbling sound, and then immediately after, a second crash,” 13-year-old Simon Korn, who lives a few houses down from scene of the accident, told The Associated Press.

Barry Gallup of Newton told WCVB-TV that he was standing on the first train when it was hit from behind. He said the impact threw him forward and on to the floor of the train.

“I may have been knocked out for a few seconds … the next thing I knew I was lying on the ground,” said Gallup, who described a confused scene in the immediate aftermath of the crash, with some passengers screaming and small fires breaking out on the side of the train.

There was no immediate word on what might have caused the crash, which occurred during rush hour on the D branch of the Green Line, part of the MBTA system which serves greater Boston.

Pesaturo said the trains would normally have been very crowded at the time of the crash with passengers heading home from the city.

Gov. Deval Patrick telephoned MBTA General Manager Daniel Grabauskas at the scene of the accident to offer any necessary assistance, Pesaturo said.

“The governor also expressed that his thoughts are with the passengers, the train crew and the emergency responders who are working to extricate this female operator from the train.”