(CNN) -- When Anthony DiSimone and Darleen Cerzosie saw fire engulfing a multifamily home on their densely packed Staten Island street early Thursday, the New Yorkers -- engaged to be married -- sprang into action. They called the fire department and ran to knock on doors to alert everyone to the danger.
The situation was grim on the second floor of 203 Chestnut Avenue; a family was trapped.
"The father was upstairs where the fire started, and he was stuck up there," DiSimone said. "He was dangling his son outside, and he couldn't do anything, the black smoke was just billowing out that window."
DiSimone, who said the boy is around 5 years old, said he shouted up to his neighbor: "I said just throw him out, throw him out!"
And that's what the father did.
"I went underneath and caught his son. He threw him right to me; I caught his son," he said.
But the father needed to get his daughter -- who DiSimone says is about 3 -- to safety as well.
"I gave (the boy) to another guy, and then (the father) brought out his daughter," he said. "My fiancee, Darleen, she actually caught the daughter."
The father eventually escaped the multifamily home, he said.
No one was killed, but 34 people -- 23 of them firefighters -- were injured in the five-alarm blaze, which is now under control, said Frank Dwyer, a Fire Department of New York spokesman.
One of those was Cerzosie, who hurt her shoulder catching the little girl.
FDNY fire marshals are investigating the cause of the blaze, Dwyer said.
CNN's Rande Iaboni and Julie Cannold contributed to this report.