SILVER SPRING, Md. (AP) — Ten people were taken to hospitals and several remain unaccounted for following an explosion and fire at a Maryland apartment building Thursday morning, authorities said.

Firefighters responded to the Friendly Garden Apartments in Silver Spring, just outside Washington, D.C., about 10:30 a.m.

Video footage from a nearby resident’s outdoor security camera shows an explosion obliterating an end unit of one building.

Steven Inman was cooking in a nearby apartment when he heard the blast.

“We heard the bang, loud shake. I see that the building is gone. My father yells out to me and I was already running over here,” he said.

Inman said he helped a woman and her small child get out of the building and found another woman with third-degree burns over much of her body.

Montgomery County Fire and Rescue Service Chief Scott Goldstein said 10 people were hospitalized, three with serious injuries.

“We do have several unaccounted for. I do not have a number to provide you at this point,” Goldstein said at an afternoon news conference.

“Our focus is to remain here until everybody is accounted for,” he added.

The building that exploded, as well as those immediately adjacent to and across from it, have been declared unsafe to reoccupy. The three buildings are home to roughly 100 people, Goldstein said.

Goldstein said there were “possible indications of alerts” by search dogs, which could indicate bodies or survivors in the rubble of the exploded building. Crews will need to bring in heavy machinery to remove an unstable freestanding wall in order to facilitate the search, he said.

Video from the scene showed flames shooting from the roof of a building and debris scattered on the ground.

Goldstein indicated that most of the flames had been extinguished by Thursday afternoon.

Authorities were hoping to escort residents back into the buildings that have been declared unsafe later Thursday so that they could retrieve belongings before being taken to shelter or hotels, and to allow residents to reoccupy three other buildings.

“It’s kind of scary looking at the extent of the explosion and it’s hard not to imagine the impact it’s had on people,” said Montgomery County Executive Marc Elrich. “It’s definitely a tough day.”

Maryland Gov. Larry Hogan tweeted that his team has been in contact with county officials about the explosion, and that the state fire marshal, state police and state emergency management officials were offering their support.

Authorities have yet to determine the exact origin or cause of the blast, but Goldstein said there had been no prior 911 calls regarding the odor of gas or a gas leak on the block since at least Jan. 1 of last year.

Washington Gas, a utility that serves the area, said it was aware of the incident and that its personnel were assisting the fire department.

“As always, the safety of our customers and community is our top priority,” the company said in a statement. “We are supporting the active investigation and do not have further details to share at this time.”

In 2016, two children and five adults were killed, and 68 people hospitalized, after an explosion and fire at the Flower Branch apartments a few miles away. After a three-year investigation, National Transportation Safety Board officials said Washington Gas’ faulty equipment was the most likely cause of the explosion. Washington Gas disputed the board’s findings.

The board also found multiple communication gaps and missed opportunities to correct the leak that might have prevented the 2016 explosion. People around the complex smelled natural gas six times in the weeks and months before the explosion, but nobody ever called the gas company to report a possible leak, investigators said.