A New York City high-rise apartment building partially collapsed Wednesday morning after a gas explosion reportedly occurred in an incinerator shaft.

The blast occurred around 8:10 a.m. at the Mitchel Houses project on Alexander Avenue in the Bronx, sending bricks and other debris plummeting to the sidewalk below, according to the New York Post.

A 20-story corner of the building was blown out, leaving a gaping hole, but miraculously there were no injuries reported.

At least 40 apartments were evacuated following the explosion, and the gas to the building was shut off, WPIX reported. Police K-9s also searched for any potential victims in 10-foot-high piles of debris.

According to the Post, the city's fire and police departments secured the building and set up a perimeter, while Con Edison, the Department of Buildings and the city's Office of Emergency Management also responded to the scene.

Shortly after the blast, New York City Mayor Eric Adams posted on X that he had "been briefed about the emergency situation taking place in the Mott Haven area of the Bronx."

"We are getting a full assessment from first responders and will continue to provide updates," Adams wrote. "Please avoid the area for your safety."

The New York City Emergency Management X account said that a temporary shelter for the building's tenants had been set up at a community center on Alexander Avenue and MTA buses had been "warranted for sheltering."

The incident unfolded as some area residents were dropping their children off at the nearby P.S. 154 Jonathan D. Hyatt Elementary School and the NYCHA Mitchel Day Care Center.

Diamond Freeman, who witnessed the collapse, told WPIX that she heard a "big boom" just before the building came crashing down.

"When you looked out, the whole building just went boom — it fell," she said. "Then you heard another boom, and all the side of the building just fell. It was crazy. All you see is smoke."

The investigation is ongoing, police said.