BOSTON (WHDH) - The National Transportation Safety Board on Saturday announced it has launched an investigation after two Green Line trolleys collided on Friday evening, injuring at least 25 people.

Emergency crews were called to the scene of the crash which occurred along Commonwealth Avenue near the Agganis Area around 6 p.m. and transported the victims to area hospitals. Firefighters confirmed that all 25 suffered non-life-threatening injuries.

The driver of the trolley was among those transported.

Crews removed both trolleys from the scene early Saturday morning and train service was fully restored on the Green Line B Branch, according to MBTA officials.

RELATED: ‘Boom!’: Green Line passenger recalls startling trolley collision

MBTA General Manager Steve Poftak said that for reasons still unknown, one trolley rear-ended another and the force of the collision derailed the train cars causing significant damage to the infrastructure.

“We will obviously get to the bottom of this. This shouldn’t happen and we will find out why it happened and we will ensure that it won’t happen again,” Poftak said. “As a tertiary matter, once we are satisfied that we have all the information we need from the scene behind us, we will begin the process of rerailing the vehicles and also making any repairs to the infrastructure that needs to be made.”

Service between Kenmore and Washington Street has been restored and shuttle buses have been phased out as of 6:51 a.m. Saturday, according to MBTA officials.

Most of Commonwealth Avenue near the Agganis Arena had been shut down in the area as crews worked to assess the incident.

Related: Transportation expert breaks down what officials will be looking for during investigation of Green Line collision

Brian Sirman who is visiting Boston from Nashville, Tennessee was on the second train at the time of the crash and said there was no warning prior to the collision.

“All of a sudden the train just jerked forward really quickly. It was like the worst amusement park ride you can imagine,” he said. “I was luckily in pa seat that was facing forward so the seat kind of caught me. I didn’t fall down but everyone who was standing, people who were sitting in the seats facing the sides all ended up on the floor. People were crying after that and a lot of people went to the hospital.”

Sirman told 7NEWS a woman who was sitting behind him may have seriously injured her shoulder.

“One girl hit her head so she had an ice pack on it. I think one guy sprained his wrist,” he said. “The worst that I saw was the girl — I think she did something to her shoulder and she looked pretty badly beaten.”

The investigation into the incident remains ongoing.

No further details have been released.

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