Firefighters remain on the scene at a west Wichita business a day after a flames first broke out.

Crews responded to Hanna Heating and Air, 216 N. West St., around 4:15 p.m. Wednesday. A passerby saw smoke coming out of the building and called 911.

Employees were inside the building when the fire started, but managed to escape. No one was hurt.

Firefighters monitored hot spots overnight, but officials said hazardous materials inside the 25,000 square feet building are making it difficult to get the flames under control.

The fire caused $1 million in damage. The cause remains under investigation.