BROWNSVILLE – An investigation is underway into what caused a deadly fire in Brownsville Sunday night.

Investigators told CHANNEL 5 NEWS smoke detectors were in the apartment, but no alarms were heard.

Gregoria Bernal lives just feet from the victim's duplex. The victim was identified as 73-year-old Cornelia Ruth Wright.

"I didn't know anything," Bernal said, "but what happened was that I heard the police and firefighters' sirens. I didn't know there was a fire. I locked myself in my room, but when I heard banging at my door, that's when I opened the door and it was the cops."

Bernal told CHANNEL 5 NEWS those officers were there to escort her out of her apartment since she did not realize her neighbor's place was on fire.

"Maybe they didn't have an alarm," she said.

Brownsville Fire Chief Deputy Cesar Pedraza said the first crews on scene took four minutes to arrive. Wright's husband was already at the front door of the duplex.

"He then stated that his wife was still inside trapped in the burning building and that she was bed confined," Pedraza said.

Wright suffered extensive burns, Pedraza said, and died at the hospital.

Pedraza said apartment fires can spread quickly, that's why the international fire codes, adopted by the city and state, require apartment complexes with three consecutive units to have working smoke detectors and sprinkler systems.

The duplex where Wright lived does not fall under those requirements.

"In this case, because of the size of the unit, they were not mandated to have a working sprinkler system," Pedraza said.

Responding firefighters also reported no smoke alarm sounded off, according to Pedraza.

"We recommend you check your smoke alarms, check your batteries, no (unattended) lit candles, heaters, space heaters, follow manufactures recommendations," he said.

With many people spending more time at home for the holidays, he added, the time to make sure smoke detectors are working properly is now.