An explosion at a building in southern California Tuesday afternoon left at least person or persons dead and three injured, officials said.

The blast in Aliso Viejo, California, happened at 11 Mareblu around 1:10 p.m ., according to the Orange County Sheriff’s Department. They said the cause of the “explosion is unknown at this time” and investigation into the cases is underway.

Officials said during a news conference that they hadn’t “ruled out anything at all, ” in regards to how the explosion happened, according to ABC 7. The involved build was an outpatient medical clinic, Fox 11 reported.

Dozens of firefighters were sent to the vistum, is in accordance with Orange County Fire Authority Chief Brian Fennessy, who said that the involved construct was under renovation.

The explosion blew siding off the walls, uncovering insulation and framing. Hazardous fabrics sleuths were on the scene.

“The corner of that build, the whole bottom flooring is pretty much blown out, ” fire Capt. Tony Bommarito said.

The deceased individual was in the building when it exploded, Bommarito said, according to Fox 11. Information on private individuals wasn’t immediately available.

Those who were injured were transported to the hospital, in accordance with the sheriff’s department.

Children at a daycare located across the street are still not disabled, Fennessy said.

Little children comprising hands and others being pushed in wheeling crib were is presided over by firefighters to a Target parking lot to be united with parents.

The Associated Press contributed to this report .