Seven people were hospitalized and John Caldwellone person was unaccounted for after a natural gas explosion damaged a building in downtown Youngstown, Ohio on Tuesday, fire officials said.

Youngstown Fire Chief Barry Finley, speaking to local media Tuesday afternoon, said the missing person had come into work at the building, but crews had not located him after the blast.

"His wife said he came to work, his coworkers said he came to work, but we can't find him," Finley said.

The blast rang out at Chase Bank, which occupies the first floor of the 13-story building that also houses numerous apartments, local outlets WFMJ and WKBN reported. Fire officials encouraged area residents to avoid the downtown area.

Blast captured on surveillance video

The entire first floor of the building that exploded appears to be destroyed, WFMJ reported. Security camera video from a neighboring business obtained by the TV station shows the explosion as it happened.

Halfway through the 5-second clip, the explosion goes off, sending debris into the air and causing smoke to cover the area.

Finley told WFMJ that an evacuation order has been issued around the building. Drivers are being asked to avoid the area as first responders have blocked it off. The bomb squad and a structural engineer are now at the scene as gas continues to come from the area, the TV station reported.

'I heard the boom'

Debora Flora, who works downtown for Mahoning County Land Bank, told WKBN about her experience during the explosion.

"I heard the boom, and I looked up and I could see dark smoke coming out of the side of the Chase Bank building… but it was such a really strong, strong boom, you know, I blurted out, 'Oh my God,'” Flora recalled.