An off-duty firefighter from the New Haven Fire Department was killed when he was hit by a car on Interstate 91 in New Haven on Monday night, according to the Connecticut State Police.

Thomas Mieles, 27, of New Haven was driving north on I-91 just south of Exit 8 when his car became disabled in the left lane around 9:30 p.m. on Monday, state police said.

Two other vehicles, a Ford Taurus driven by a 25-year-old West Haven woman and a Chevrolet Silverado driven by a 48-year-old Southington woman, stopped in front of Mieles’ vehicle to assist him, state police said.

A fourth vehicle, an Acura TLX driven by a 63-year-old Middletown man, was traveling in the left lane when it struck Mieles’ vehicle, driving it into the Ford. The Acura continued forward, sideswiping a Chevrolet Equinox on its driver’s side and the Silverado on its passenger side, state police said.

After being hit, the Equinox, driven by a 32-year-old New Haven man, went into the left lane and hit Mieles, who was outside of his vehicle.

Mieles sustained life-threatening injuries and was transported to Yale New Haven Hospital where he was later pronounced dead, state police said.

The drivers of the Silverado and Acura sustained minor injuries and were transported to Yale New Haven Hospital. The driver of the Ford sustained minor injuries and was transported to St. Raphael’s Hospital.

The driver of the Equinox and a child in the Silverado were not injured in the crash, state police said.

Mieles was a new member of the New Haven Fire Department and was stationed at the East Battalion Headquarters on Lombard Street.

He grew up in New Haven near the station, went to Wilbur Cross High School and joined the department in January when he graduated from firefighter training, according to New Haven Fire Chief John Alston.

“Thomas loved the fire department,” Alston said at a press conference on Thursday. “He was just hired in January, but one of the most exciting things he had was to work in this house with the people that are here with me. Growing up in his neighborhood and being able to protect his own neighborhood, I understand how proud he probably was.”

A fellow graduate of the 63rd class of New Haven firefighters, Ibrahim Cheek, said Mieles was “very full of life.”

“He loved his job, real good-hearted person, talked a lot, but very good-hearted,” Cheek said. “Just like him, I’m sure he was extremely proud to serve his city, just like all of us are. A really big loss, a really big hit to the department. I’m just glad I got the chance to know him.”

The New Haven Fire Department has lost a member of each of its last three classes, including William McMillian, Ricardo Torres and Mieles.

“It’s an awful day for New Haven firefighters,” said New Haven Firefighters Union President Patrick Cannon.”Our hearts are full of sorrow. We lost another brother — a young, energetic, full-of-life firefighter who was happy to be here, happy to do the job, and happy to be a part of the New Haven firefighter family.”

New Haven Mayor Justin Elicker said Mieles’ death was a tragic and devastating loss for the city.

“At 27 years old, we lost Firefighter Mieles while he was far too young,” Elicker said. “Our hearts break for his family, his fiancé and his brothers and sisters at the New Haven Fire Department. The city of New Haven is committed to doing everything we can to support the Mieles family and to ensuring that the New Haven Fire Department has every resource it needs to get through this difficult time.”

All New Haven city and department flags were ordered to be lowered to half-mast in honor of Mieles’ service.

State police are looking for witnesses to the crash. Anyone with information or footage of the crash is asked to contact Troop I at 203-393-4200.