A chemical spill in Sapulpa caused a two-hour evacuation of homes and businesses near 61st Street and Southwest Boulevard.
Sapulpa Fire Department, as well as the Tulsa Fire Department's Hazmat crew are on scene.
The fire chief said it started in the chemical storage area at Sulzer Chemical Technologies, on Route 66 just South of 61st Street, and among what's burning is nitric acid.
They had to wait to put water on the fire because they needed to contain the toxic run-off, the chief said.
The evaluation order has been lifted, but crews will be cleaning up the area all night, according to the fire department.
No injuries were reported.