A Signal Hill resident is in critical condition after a fire broke out at an apartment complex early Monday morning.

The fire was reported about 2:45 a.m. in the 2200 block of Gaviota Avenue, the Los Angeles County Fire Department stated on Twitter.

Heavy smoke and fire was showing from a second-story unit when firefighters arrived, prompting officials to evacuate the multi-unit building.

As crews worked to extinguish the blaze, firefighters discovered a man in cardiac arrest inside one of the units.

Emergency personnel were able to find a pulse on the victim as he was being transported to the hospital, where he is listed in critical condition Fire Inspector Joey Marron said.

A fire official initially said one person had died and a second victim was transported, but it was later determined only one person was involved in the incident.

Firefighters put out the blaze in about 20 minutes, Marron said.

Residents who evacuated the building were allowed to return later in the morning, except for one unit directly below the fire, which sustained water damage during the attack.

“I’m still shaking right now … It’s just scary,” a resident named Charisma told KTLA.

The man who was hospitalized had been sick for some time and used an extra oxygen supply to help with his breathing, Charisma said.

Investigators were working to determine a cause for the fire.