July 3 (UPI) — Four people were injured in an explosion at a Tokyo bar on Monday that police said may have been caused by a gas leak.

The bar owner was among the four victims hurt in the blast on Monday afternoon in the Shimbasi district.

“I thought I could smell something like gas or sewage in the smoking area and when I used a lighter to light a cigarette there was this explosion,” the owner said.

Other victims included another employee of the bar and two passersby

Authorities later found a higher-than-unusual concentration of gas in the bar, located on the second floor of a building.

The explosion resulted in a fire, that was later extinguished.

The restaurant is about 1,000 feet away from the JR Shimbashi Station. The area was closed and police told passersby to stay about 100 meters away from the site.