NEW YORK (NewsNation Now) — At least nine people — six of them children — were injured in a gas explosion at a Bronx home Thursday afternoon.

NewsNation affiliate PIX11 reports two children injured are in critical condition with life-threatening injuries, while two others have injuries deemed serious but not life-threatening. The rest suffered minor injuries.

There was a gas explosion on the building’s second floor, blowing out most of the windows and doors, but officials said the cause remained unknown. Emergency crews received the call just after 3:20 p.m. Thursday for a report of trauma, an FDNY spokesperson said.

“There was a gas smell,” Miguel Sambolin, who was inside the building told PIX11. “I left all the doors open so the gas smell would leave — that’s when I heard the explosion.”

Elvis Copa said he doesn’t live in the building, but saw what happened and ran inside to help a woman with a young child.

“I heard the lady screaming because she had the baby right there, so I ran in and grab the baby,” he said, describing the baby as likely 4 to 6-months-old.

The youngest child injured, officials said, is 3 years old.

The explosion happened on Paulding Avenue, at a home at the street’s dead end, near Poplar Street, according to FDNY. Everyone made it out of the building, which is a three-story multi-family home.

About 125 firefighters and EMS personnel responded; the situation was deemed under control by about 4:40 p.m., FDNY officials said.

WPIX contributed to this report; all reporting by Corey Crockett, Aliza Chasan and Jennifer Bisram