A courageous building super lept into action and helped save three young children from a burning third-floor apartment in Brooklyn on Friday, according to witnesses.

Chris Krauch, 58, told The Post he heard a “whoosh” of flames burst through the windows of the East New York apartment around noon — followed by a man frantically screaming, “help!”

“We kicked the door open and tried to go up the stairs but there was too much stuff blocking the stairs,” he said, adding the smoke had become too overwhelming to try to get to the apartment at 494 Hendrix St.

Krauch — who was in the backyard when the blaze began — teamed up with another man from the neighborhood to save the youngsters. He got up to a second-floor window and had the tot’s dad hand the kids down from the third floor.

“Me and another guy, who ran from across the street, climbed onto a window sill and grabbed the babies as the father handed them down,” he said.

“They were young kids”

“The dad wanted to throw the kids out the window,” he added. “Everyone yelled ‘don’t throw them’.

“If he threw ’em, you’re going to end up with a dead baby.”

A relative of the family said the parents have eight kids. Four were in the building while the rest were at school at the time of the fire — and the ones who had to be rescued were ages 10 months, 3 and 4.

“My sister’s in shock, but she said everybody’s OK,” relative Samantha Reynoso said.

“She didn’t say anyone was injured but they’re all in shock.”

She added that the family had a tragedy last year when one of their kids, then aged 11, was hit and injured by an ice cream truck.

The boy was at school at the time of the blaze.

The FDNY arrived shortly after and rescued the parents, Krauch said.

The super said the family had been taken to the hospital, but they all escaped with no injuries.