The apartment in Trump Tower in New York where a fire killed a prominent art dealer and collector and injured six firefighters had no sprinkler system.
The fire started on the 50th floor of the Manhattan building just before 10 p.m. EDT Saturday.
At a press conference Sunday, New York fire commissioner Daniel Nigro said the apartment was "virtually entirely on fire'' when firefighters arrived.
The fire sent thick, black smoke pouring from the windows of the skyscraper that bears the U.S. president's name.
Fire sprinklers were not required in New York City high-rises when Trump Tower was completed in 1983. Subsequent updates to the building code required sprinklers to be retroactively installed in commercial skyscrapers, but only if the building underwent major renovations.
U.S. President Donald Trump was among the developers who spoke out against retrofitting older buildings as expensive and unnecessary.
The man killed in the blaze was identified Sunday as Todd Brassner, 67, who bought the apartment in 1996.
Brassner is mentioned several times in artist Andy Warhol's posthumously published diaries, with references including lunch dates and shared taxis. Warhol signed and dedicated at least one print to Brassner.
Brassner had in recent years struggled with health and finance issues, filing a bankruptcy in 2015.
No member of the Trump family was in the 664-foot tower on Saturday.
Trump's family has an apartment on the top floors of the 58-story building, but the president has spent little time in New York since taking office. The headquarters of the Trump Organization is on the 26th floor of the building.