A massive explosion leveled a Maryland apartment building and seriously injured 3

• A Maryland apartment building exploded on Thursday morning. The explosion reduced it to rubble.
• Three people were seriously injured in the blast, which remains unexplained, officials said Friday.

A massive explosion at a Maryland apartment building on Thursday seriously injured three people and landed another 11 people in the hospital, local officials said on Friday morning.

Early on Thursday, the explosion reduced a building in the 2400 block of Lyttonsville Road in Silver Spring, Montgomery County, to rubble and led to a blaze that saw around 150 firefighters called out, said Pete Piringer, the public information officer at Montgomery County Fire and Rescue Service.

Piringer described it as a "catastrophic event where the building basically exploded and collapsed."

John Bell, a nearby resident whose home was unharmed, told the local outlet WTOP that the explosion "shook it like an earthquake."

No one was killed in the blast. As of Friday, officials were working to confirm whether there were any visitors at the time of the blast, but all residents were accounted for, Piringer said at a press conference.

Footage of flames engulfing the building were shared by local news organizations and neighbors.

The cause of the explosion remains unknown. County Executive Marc Elrich said prior to Friday's briefing, "We have reasons to believe that there may have been a human error of sorts there," WTOP reported.

The maintenance worker is providing information to investigators, Piringer said at the briefing. He said one "investigative theory" was that the explosion was linked to maintenance work at the building.

Elrich added that the building had a fire inspection on February 2 and its full triannual building inspection last October.

Around 240 people in neighboring buildings were evacuated on Thursday. Six buildings were still without power on Friday as a result of the damage to a nearby transformer, Piringer said.

Montgomery County's government tweeted a fundraiser for all those affected by the disaster.