Fire officials say they are investigating the cause of a fire at an apartment building on Fourth Avenue in Fort Hamilton that left one person in critical condition and a firefighter with minor injuries. Firefighters tell News 12 the call for the fire came in after 7 a.m. and was under control just before 7:50 a.m. They say it started on the second floor of the building. News 12 spoke with a resident who wanted to remain anonymous, but says he called the firefighters when he awoke to the sounds and smells of that fire. “I heard the fire alarm; I went to the door and felt the knob it was pretty hot. I opened the door, there was smoke everywhere, I ran downstairs and called the fire department. Thank goodness they’re a block or two away they were here within minutes. It could’ve been a lot worse," he said. Another resident, Mario Rodriguez, says it was a scary scene. “In that moment we started running. We wanted to help people on the second floor. The guy on the second floor didn’t want to leave until help came," said Rodriguez. The Red Cross says it is currently helping three adults and two children whose homes were impacted by the fire. It says if anyone else impacted needs help, they can call 877-RedCross (option1). The cause of the fire was not known as of Thursday evening.