7 injured, 2 missing after explosion rocks downtown Youngstown, Ohio

Seven people were injured, including one critically, and two people remain missing after an explosion rocked downtown Youngstown, Ohio, Tuesday, officials said.

The explosion occurred near Central Square Tuesday afternoon, police said, urging people to avoid the area.

It is unclear what caused the explosion, which impacted a building that contains a Chase bank and apartments, authorities said.

Youngstown Fire Chief Barry Finley had initially characterized the incident as a natural gas explosion, but later said crews were working to determine if there was a gas leak.

"All I know for sure is that there was an explosion," Finley told reporters during a press briefing Tuesday evening.

Mercy Health said Tuesday evening it is treating seven people who were injured in the incident, including one person in critical condition.

Following a search of the building, a man and woman remain unaccounted for, Finley said. The man is an employee of the bank, the fire chief said. Police were searching for his vehicle in the wake of the explosion, he said.

"Until then, we have to assume he is in the building," Finley said.

The floor collapsed into the basement, which was flooded, and search crews were working to send a mini-drone in there to aid in the search effort, Finley said.

The Chase bank is located on the ground floor of the building, with apartment units on the 12 floors above.

The building has been evacuated and streets in the surrounding area have been closed to traffic indefinitely due to the potential for a structural collapse, authorities said.

A Chase spokesperson told ABC News the company is in "close contact with local officials to check on the safety of everyone in the building and area."

"After that, we'll work to determine what happened and to assess the damage," the spokesperson said.

There is no evidence of any suspicious activity at this time, officials said.