WATERTOWN, Mass. (AP) — A firefighter who collapsed and died after responding to a house fire Friday morning was a 21-year veteran of the department and a married father of five children, colleagues said.

Town and fire officials in Watertown say 54-year-old Joseph Toscano, of Randolph, suffered a medical emergency as he and others battled the morning blaze at a residence in the Boston suburb.

He was rushed to a nearby hospital, where he later died. The cause of death is still under investigation, but officials say it might have been a heart attack.

Deputy Fire Chief Robert Quinn said Toscano was an experienced and trusted 21-year veteran of the department who served as his “eyes and ears” inside fire scenes. He said Toscano was stationed at the fire department headquarters for most of his career and had served as his driver.

“We never expect this day to happen, but it happened,” Quinn said. “It’s a tough job. It really gives you a punch in the face to see this happen.”

Toscano is the first Massachusetts firefighter to die in the line of duty since 2014, when two Boston firefighters were killed battling a fast-moving blaze in Back Bay, according to the state fire marshal’s office.

Quinn said nothing seemed amiss when he spoke with Toscano earlier in the day. Toscano was planning to cook a pasta and shrimp dish for the crew’s St. Patrick’s Day meal because he didn’t like corned beef and cabbage, he said.

Firefighter Union President Robert Mannix described Toscano as a family man who leaves a wife and five children.

“Everyone is devastated,” he said.

Toscano’s family said in a statement Friday night that “family was at the center” of his life and that it “defined him.” He also loved being a Watertown firefighter, they said.

“Joe’s work ethic, generosity and kindness touched everyone he knew,” they said.

Watertown Town Manager Michael Driscoll said residents in the town would help the family in any way they could. “It’s a very sad day,” he said. “We’ve lost a fallen hero.”

Republican Gov. Charlie Baker tweeted his condolences Friday afternoon to the family and to Watertown firefighters.

State Fire Marshal Peter Ostroskey said that his office is investigating the cause of the fire but that it doesn’t appear suspicious. The fire was mostly confined to a second-floor room.

Two people and their pets were evacuated from the home. One of the residents suffered an undisclosed injury.

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