A Commuter Rail train headed to Boston struck a car on the tracks on Friday morning in Belmont, injuring a woman who had exited the vehicle to let out the three children in the backseat, authorities said.

The 58-year-old woman, whose name was not released, was taken to Beth Israel Hospital and was listed in serious condition, officials said. Only one of the children was still inside the vehicle at the time of the crash, but none were injured, authorities said.

The incident is under investigation, and it was not immediately clear why the car was on the tracks as the train approached.

 

Three children who remained in the car — including her son — were not seriously injured.

The inbound Fitchburg Line train hit the woman's vehicle at the Brighton Street crossing at about 8 a.m., MBTA Transit Police Superintendent Richard Sullivan told reporters.

The woman's 11-year-old son and a 10-year-old boy had gotten out of the car, but a 6-year-old boy was still inside at the moment of impact, Sullivan said. All three of the children were taken to the hospital as a precaution, he said.

The woman's car was on the tracks while the crossing arm was down to signal an approaching train, Sullivan said. The woman then exited her vehicle, and tried to open the back doors to let the children out when the train hit her car, which then struck her.

"We do not want anyone to jump to conclusions as to how this happened," he said. "It's a very tragic situation. Our thoughts and prayers are with everyone in that vehicle."

Sullivan said the train operator attempted to stop, but because the crash was still under investigation, he could not say how fast the train was going when it struck the vehicle.

A preliminary investigation found there was no traffic backup that could have caused the driver to get stuck on the track, and it also found the crossing mechanisms were all fully operational, Sullivan said.