BALTIMORE, Md. (WDVM) — The Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) said on Wednesday that the deaths of three Baltimore firefighters in a January fire were homicides.

On January 24 around 5:53 a.m., the Baltimore City Fire Department responded to a fire in a vacant row home. As they were responding, the building partially collapsed, trapping four firefighters inside.

One firefighter was extracted and transported to Shock Trauma, but rescue efforts continued throughout the day until they located the other three, who had died.

ATF released a statement saying that the cause of the fire was incendiary, or “a fire that is intentionally ignited or spread into an area where the fire should not be.”

The release said that a person of interest who was in photos and videos has been identified and “no additional tips from the public are needed.”

The investigation into this fire is still ongoing.