FRESNO, California -- A fire that broke out Sunday at an abandoned home in Fresno, killing five people and critically injuring another, authorities said.

Fire crews pulled six people out of the boarded-up home engulfed by flames and thick smoke, Battalion Chief Lawrence French said. Four were pronounced dead at the scene, and the other died at a hospital.

A neighbor told police he heard people screaming for help and pounding against a window, French said.

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The injured person, who is in critical condition, is being treated at Community Regional Medical Center, the Fresno Bee reported.

All the dead were adults, said Tony Botti, spokesman for the Fresno County Sheriff-Coroner's Office.

CBS affiliate KGPE reports that the Fresno County Coroner identified three of the victims as Anthony Zavala, 37, Irene Hinojos, 36, and Monique Amaral, 28.

Fire investigators are expected to remain on scene throughout Sunday to determine what caused the fire, French said.

The house in Archie Avenue had been vacant for many years, and most doors and windows had been boarded-up, Fresno fire spokesman Pete Martinez said.

One of the boarded-up windows had been pried open by people who were squatting, and that was the only way for the occupants to enter or exit the house and was also where the fire was the most intense, he said.

Firefighters found the six victims in one of the bedrooms where it appeared they were trying to smash a window to get out.

Martinez said it looked like the victims may have died from smoke inhalation but that the cause of death has not been determined.