(NewsNation Now) — Investigators have determined the fire that claimed the lives of 17 people on Sunday in New York City was started by a malfunctioning space heater­ ­–  a device responsible for nearly 15% of all home-fire deaths.

The weekend blaze at a Bronx high-rise is already the city’s deadliest in three decades. It was originally reported that 19 people, including nine children had died. Those numbers were updated on Monday.

Doctors are working to save the lives of several people gravely injured when smoke from the fire knocked them out or trapped them in their apartments. Seventeen people, including eight children, died in the blaze. Dozens of people were in the hospital Monday, and as many as 13 were in critical condition.

According to the National Fire Protection Association, heating equipment fires have been responsible for killing 480 people and causing more than $1 billion in property damage over a five-year period.

Space heaters, in particular, were responsible for only 4% of all fires, but they were at the root of 15% of all home fire deaths.

In fact, a 2020 fire in the Bronx caused by a space heater killed four women in neighboring apartments and injured a fifth.

The U.S. Fire Administration reported that when the cause of a fire had been determined, portable electric space heaters were the object most responsible for home deaths in New York state alone.

Fire safety experts have said to never use a space heater with an extension cord and keep the device clear of all combustible materials, as those are the two most common causes of space-heater fires.

The Bronx fire happened on the heels of Wednesday’s deadliest single fire in more than two decades in Philadelphia.

The cause of that fire, which killed 12 people, including eight children, remains under investigation.

Investigators last week were looking into whether a 5-year-old who was playing with a lighter might have sparked the deadly conflagration by setting a Christmas tree on fire.