(CNN) -- A taxicab plowed into a group of cab drivers sitting outside a taxi pool in East Boston on Monday afternoon, leaving 10 people injured, Massachusetts State Police said.

Two law enforcement sources told CNN the incident is being treated as an accident, not an act of terrorism. The driver told authorities at the scene he accidentally hit the gas instead of the brake, according to both sources.

There was a large law enforcement response to the 1:40 p.m. ET incident at Porter Street and Tomahawk Drive near the Logan International Airport taxi pool. The area is just west of the airport.

Speaking at a news conference, Massachusetts State Police Maj. Frank McGinn said, "One of the cab drivers in the pool had jumped the curb and struck some fellow cab drivers sitting ... there waiting for their next fares."

The driver was cooperating with authorities and was "known to be a very nice gentleman," McGinn said.

McGinn said it appears all the injured people are fellow cab drivers. The most seriously injured person has broken legs and "maybe some internal chest injuries," he said.

Ana Vivas, media relations manager at the Boston Public Health Commission, said four patients were taken to Boston Medical Center, four to Tufts Medical Center and two to Massachusetts General Hospital.

In a news release, the state police said the cab driver was a 56-year-old Cambridge man. His identity has not been released and the cause of the crash is under investigation, according to state police.

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MSP, @bostonpolice, @BostonFire, @BOSTON_EMS onscene. Preliminary reports indicate several pedestrians with injuries, varying severity. https://t.co/2bqBJYDOh3

— Mass State Police (@MassStatePolice) July 3, 2017