DENVER (KDVR) — Crews from West Metro Fire Rescue responded to a structure fire in Lakewood around 9:30 a.m. Tuesday.

According to WMFR, a passerby noticed smoke at a storage facility at the intersection of West 13th Avenue and Depew Street.

The assistant chief told FOX31’s Lisa D’Souza that the building where the fire started had been abandoned for some time, and there had been groups of unhoused people staying in it off and on for several months.

This was not the first fire in the building that was believed to have been caused by the transient people living there, but because of the size, there was concern the fire would spread.

“The biggest challenge is that we don’t know who’s in the building since it’s not supposed to be occupied,” the assistant chief said.

By 10 a.m., WMFR said the fire was under control, although there were expected to be traffic impacts as cleanup continued and crews cleared the scene.

The official cause of the fire remains under investigation, but the assistant chief said it was likely started by someone staying in the building illegally.