An on-duty Chicago firefighter performed CPR on his wife after rushing to a fire in his Far Northwest Side home Tuesday night that also seriously injured the couple’s three children, according to the Chicago Fire Department.

The 34-year-old mother and three young children were pulled from their bedrooms and hospitalized in critical condition with smoke inhalation, authorities said. The children are two girls aged 2 and 7 and a 7-year-old boy.

The firefighter was not working with the crew that responded to the home in the 2500 block of North Rutherford Avenue in the Montclare neighborhood at 9 p.m., but he was driven there by a department member, CFD spokesman Larry Langford said.

When he arrived, the father was performing CPR on his wife, Langford said.

The cause of the fire remains unclear, but investigators know it started in the kitchen and spread throughout the home, Langford said.

Smoke alarms in the house worked, he added.

The day after the fire, contractors folded up broken windows and a door on the home’s porch, where an empty pram stood.

Neighbors passed by and told reporters about the quiet working-class family who have lived in the home for several years.

“We’re praying for them,” Carlos Gomez said as he walked his dog. He said he saw firefighters remove children from the home and perform CPR. “I hope they’re all right,” he said.

Justin Castrejon said he lives across the street and helped the family’s mother last fall after she locked her keys in the car.

“She said, ‘Thank you very much,'” he said. “They were pretty quiet. I just feel bad.”

Ald. Gilbert Villegas (36) visited the victims’ homes on Wednesday morning. He said firefighters would search the block and send out smoke alarms with 10-year battery life.

“We pray for the wife and children to be healthy and have a speedy recovery,” Villegas said.

Villegas said he recently met the family while on his way to an election.

“They are a working class family. The family was just your typical Chicago family in the bungalow belt. They keep to themselves, Villegas said.

Neighbor Julisa Miranda said she was shocked by the fire.

“I’ve never seen so many firefighters,” she said. After this I thought, ‘Am I prepared?’ I’m not.”