A 95-year-old man and his 71-year-old son were both critically injured in an apartment fire in SoHo.

Officials say flames broke out on the fourth floor of the building on Sullivan Street just before 9 p.m.

Neighbors say the fire smelled electrical and that they didn’t her a smoke detector go off. Video from inside the building shows water damage to some neighboring apartments.

“I heard a knocking on my door, a loud bang, then I hear someone yelling in the hallway,” resident Korey Benesh recalled.

Both men who were injured have been there for decades as longtime residents.

Authorities say one other resident and three firefighters were treated for minor injuries.

FDNY Deputy Chief Michael Barvels says there was clutter in the apartment and the narrow hallways made the operation difficult.

“You could only fit one person down the hallway at a time. On top of that, trying to move within that apartment is difficult because of all that clutter,” Barvels said.

The fire was placed under control, but the apartment is badly burned. Fire investigators will work Tuesday to determine what caused this fire.