As a fatal fire in a 50th-floor apartment in Trump Tower on Saturday began to worsen, the flames triggered a system of smoke sensors, but no sprinklers; the building was built in the 1980s, before such systems were required in new residential towers.

In 1999, after a pair of fatal apartment tower fires, New York City passed a law requiring new apartment buildings to install sprinkler systems. Older buildings were exempt: Developers at the time, including Donald J. Trump, resisted calls to require older buildings to retrofit with sprinkler systems in each apartment, arguing it would have been very costly.

But after the deadly fire on Saturday, city officials on Monday suggested that it was time to revisit the issue.

Robert Cornegy Jr., the chairman of the City Council committee on buildings, called for legislation to require older apartment buildings like Trump Tower to install sprinkler systems.

“We have to be more conscientious on behalf of residents,” Mr. Cornegy said, adding that lives should be protected at “any amount of expense.”

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Trump Tower does have a system of smoke sensors, and they activated an alarm that automatically was routed to the Fire Department, according to a department official.

A sensor in the building’s ductwork detected smoke and an alarm was sent to the Fire Department at 5:35 p.m. Saturday, according to the official, who asked not to be named in order to talk about an investigation that was still in the preliminary stages.

Firefighters arrived at the Fifth Avenue building, where President Trump has a triplex, four minutes later. Investigators believe the blaze may have started as an electrical fire in the apartment bedroom, the official said.

In the meantime, the building staff saw the alarm had been triggered and one or more employees went to the 50th floor to investigate. They noticed smoke coming from apartment 50C and opened the door, the official said, but the smoke and fire were already too intense for them to enter the apartment and try to save the owner, Todd Brassner.

The official said that there was no working smoke alarm in the apartment, such as the type of battery-powered alarms that homeowners typically install.

Mr. Brassner, 67, died from burns and smoke inhalation, the official said.

The head of the Real Estate Board of New York, an industry association, pushed back against the call to retrofit older buildings with sprinklers. “The City’s Building Code has proven to be effective at significantly preventing fires in high rise multifamily housing or limiting their impact to a single residential unit in a building,” John H. Banks, the board’s president, said in an emailed statement. The statement listed obstacles to a blanket order to retrofit, such as cost and lack of adequate water supply in many buildings to operate a sprinkler system.

Mr. Brassner was an art dealer and a collector who had become something of a recluse in recent years, according to friends. He had a collection of about 100 vintage electric guitars, 150 ukuleles, and artwork by artists such as Andy Warhol and Robert Indiana. The official said that all the contents of the apartment were destroyed in the fire.

The fire was contained to Mr. Brassner’s apartment, but there was significant smoke and water damage in the building as a result of the fire and the efforts to fight it. The official said that smoke reached the building’s upper floors where Mr. Trump’s triplex is, but did not cause damage.

Residents of the building said that no alarm went off to alert tenants of the emergency. Miles Fisher, an engineer who designs fire alarm systems, said that is standard protocol. He said that residents in fireproof high-rise apartment buildings like Trump Tower are instructed to remain in their apartments in case of fire elsewhere in the building and place wet towels at the base of their doors to keep smoke out.

Miriam Light, 67, a commercial and residential landlord who lives on the 39th floor of Trump Tower, said that she learned about the fire only when her father called from Florida while watching it on the news. She said that she left the building and returned later to find no damage to her apartment.

She praised the Trump Tower staff but said that it was time for the building to improve its fire safety system, including the addition of sprinklers.

“It’s the 21st century,” Ms. Light said. “Nobody has to lose their life. The system should be updated. Whatever it takes, it should be improved.”

Michael Tobias, a mechanical engineer who works with fire safety systems, called for a law requiring older residential buildings to install sprinklers.

“It’s a very big gap in New York fire safety,” he said.

Yash Dongre, 27, said he lives in an apartment directly under Mr. Brassner’s unit.

He said he was home at the time of the fire and when he smelled smoke he decided to rush down the 49 flights of stairs. He said that he heard an alarm from the floor above.

“I could see the smoke filling up in my apartment because the building has a central ventilation system because the windows are sealed. The smell came through the ventilation system.

“I think every apartment should have sprinklers but I also understand this is an old building.”

Mr. Brassner bought the apartment for $525,000 in 1996, according to city records. He had financial problems over the years, and as early as 2003 the building’s condominium board placed a lien on the apartment for failure to pay common charges, according to city records.

In 2013, city records show that a lien was removed from the apartment after Mr. Brassner paid $21,668 in arrears and fees.

Friends said that Mr. Brassner wanted to sell his apartment, but there is no record of the apartment having been listed with a broker.

The original article was written by William Neuman in The New York Times on April 9, 2018.