OMAHA, Neb. (AP) — Authorities say some people have reported smelling natural gas before an explosion in Omaha’s Old Market area, but the authorities say no one called 911.

Firefighters stopped pouring water into the burned-out building on Monday morning. It had housed a restaurant and several apartments before going up in flames after Saturday afternoon’s blast, which resulted in injuries to two people.

Omaha Fire Chief Bernard Kanger says no calls about the odor were found in a review of 911 recordings made as far back as three hours before the explosion. Metropolitan Utilities District officials also say there were no calls about the odor before the blast.

Kanger says investigators haven’t yet concluded what caused the explosion.