A massive brick chimney running 20 stories up the side of a New York City apartment building collapsed after an explosion Wednesday, sending tons of debris plummeting to the ground.

The falling bricks buried a sidewalk, landed on the playground of the public housing building and sent a cloud of dust billowing over the block in the Bronx, but amazingly did not injure anyone.

“We avoided a major disaster here,” said Bronx Borough President Vanessa Gibson at a news conference.

Mayor Eric Adams confirmed no injuries or deaths were reported in the collapse of the chimney, which rose up the side of the building from the boiler room. Authorities learned of an explosion just after 8 a.m. and were trying to determine if there had been a gas leak.

The mayor noted that Oct. 1 is typically the first day that heating systems are turned on for the season.

City officials in charge of public buildings said they were investigating to see what went wrong, and Department of Buildings Commissioner James Oddo said he believed work was being done on the boiler.

Some apartments were being evacuated as a precaution and services for residents were being made available at a nearby community center, officials said.

The city’s Emergency Management Commissioner, Zach Iscol, said building inspectors are checking the building’s foundations and the apartments in the impacted area to make sure they are sound. The mayor said the building will be repaired.

Around half a million New Yorkers live in aging buildings run by the city’s housing authority, known as NYCHA, which is the largest in the nation.

Many of the properties date back to the 1940s, ’50s and ’60s. In 2019, a federal monitor was appointed to address chronic problems like lead paint, mold and lack of heat. When he wrapped his five-year term in 2024, the monitor, Bart Schwartz, noted that the overarching issue for residents remained the “poor physical state of NYCHA’s buildings.”

(The Associated Press contributed to this report.)