CHICAGO (NewsNation) — Multiple people were hospitalized Tuesday after a building explosion in Chicago, according to reports.

The Chicago Fire Department said at least eight people were transported to the hospital. Officials told NewsNation affiliate WGN-TV that three people were in serious to critical condition.

As of Wednesday morning, Chicago Alderman Chris Taliaferro confirmed on “Morning In America” that some had been released from the hospital but those listed in very serious or critical condition remain hospitalized.

First responders were on the scene at a four-story, 36-unit apartment building in the city’s South Austin neighborhood on the West Side just before 9:30 a.m CT. At least 10 ambulances were on the scene.

“My thoughts are with those who were injured and displaced in the building collapse in the Austin neighborhood,” said Mayor Lori Lightfoot. “We must also thank the brave men and women of the Chicago Fire Department who are working to abate the dangerous conditions.”

The building next door was evacuated, according to fire officials. Fire officials had also requested a mass casualty ambulance bus, according to NBC Chicago.

“Our first concern is the health, well-being and safety of our residents,” Roman Viere, owner of the building, said in a statement. “We are doing everything we can to cooperate with emergency services, and we are ready to do whatever we can to support our residents.”

No cause of the explosion had been determined. The department said in a series of tweets that the Chicago police bomb squad and agents from the federal Bureau of Alcohol, Tobacco, Firearms and Explosives were on their way as well.

NewsNation affiliate WGN-TV contributed to this report.

This is a developing story.