Green Line trolley was going 30 mph in 10 mph zone when it hit second train Friday

Investigators at the scene of a crash between two Green line T cars on Commonwealth Ave. after they collided.Barry Chin/Globe Staff/file

A Green Line trolley was hurtling along the tracks at about 30 miles per hour Friday when it crashed into the trolley ahead of it, injuring 25 people, according to a preliminary investigation by the National Transportation Safety Board.

The speed limit for trolleys in that area is 10 miles per hour, an MBTA spokesman said Monday. The other trolley in the crash was going 10 mph, the NTSB said.

The new information came hours after Governor Charlie Baker had expressed concern about the trolley’s rate of speed.

“I’m really anxious to find out exactly what happened because this could have been a far more significant incident than it was, given the estimates that are out there about how fast that train was traveling when it hit the other train,” Baker told reporters at a housing event in Everett.

The NTSB jumped into the investigation one day after the incident, in which a trolley traveling westbound on the B branch struck another trolley from behind near Babcock Street and caused visible damage to both vehicles.

First responders provided medical attention to 25 people after the crash, according to the MBTA. Baker, who said he spoke with Transportation Secretary Jamey Tesler several times over the weekend, told reporters Monday that “thankfully, everybody there seems to be OK.”

The MBTA placed one Green Line driver, a seven-year veteran who was operating the front car on the trolley that struck the other vehicle, on administrative leave. Other drivers have not been placed on leave.

Shuttle buses replaced trolleys in the affected area Friday night, and standard train service resumed Saturday morning.

“We will obviously get to the bottom of this. This should not happen, and we will find out why it happened and ensure it won’t happen again,” MBTA General Manager Steve Poftak told reporters at the scene Friday.

The NTSB, a federal agency that examines transportation-related accidents and pipeline incidents such as the 2018 Merrimack Valley gas explosions, deployed four investigators with specialties in “operations, crashworthiness, and human performance” to the scene of the Green Line crash, a spokesperson said.

“At this early stage of an investigation, NTSB does not state a cause but will provide factual information when available,” NTSB spokesperson Jennifer Gabris said in a statement on Monday. “Investigations involving injuries and other major investigations currently take between 12 and 24 months to complete. A preliminary report is expected to be published in a few weeks.”

Material from State House News Service was used in this report.