A one-alarm fire tore through a home in Lynn late Thursday night, injuring a firefighter, displacing a family of four, and killing their dog, authorities said.

Lynn Fire Lieutenant Sean Martin, 42, sustained a shoulder injury after falling from the first floor to the basement through a gap where a staircase had recently been removed, according to District Fire Chief Steven Archer. Martin was treated and released from NSMC Union Hospital.

Firefighters were called to the home on Ontario Street after the residents awoke to the sound of crackling flames at 11:37 p.m. Thursday.

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“Everyone got out of the house safely, but the damage to the house was extensive,” Archer said. Flames were concentrated in the 2½-story, wood-frame home’s kitchen and attic. The rest of the home suffered extensive water damage.

The American Red Cross responded to assist the family of two adults and two children, ages 3 and 6.

“[They are] now in a hotel after losing everything this morning,” said Kat Powers, a Red Cross spokeswoman, in a statement. They were also given money for food, winter clothing, and infant supplies for the youngest child, the statement said.

Firefighters were at the scene until about 2 a.m. today. The cause of the fire is currently under investigation by Lynn detectives.

Firefighters from Swampscott, Peabody, Saugus, Malden, Salem, and Revere assisted in the response, Archer said.