Firefighters were working to extinguish a fire at a recycling facility Tuesday in south Houston.

Crews were initially dispatched for a trash fire, but the response was upgraded after they arrived. About 26 units and additional support personnel responded, the department said.

“HFD Hazardous Materials personnel and representatives from CIMA and the Texas Commission on Environmental Quality are on scene conducting air quality monitoring,” the department said in a 10:44 a.m. post. “At this time, no environmental concerns have been identified.”

The cause of the fire remains under investigation by the HFD Arson Bureau.

The Houston Chronicle reached out to the fire department for more information.