At least three people were killed in a shooting inside a Walmart store on Wednesday in suburban Denver, where police said they had not yet taken anyone into custody.

Two men were killed in the shooting. A women, who was injured in the shooting, was taken to a hospital where she later died, Thornton Police Department said on Twitter.

Police in Thornton, Colorado, did not release any information about any of the victims and it was not clear if an assailant had been taken into custody. Thornton is about 10 miles (16 km) northeast of Denver.

Reports of shots fired came shortly before 6:30 p.m. Mountain Time, a police spokesman told local 9NEWS in Denver. Local television images showed a number of police cars and ambulances surrounding the store, lights flashing.