Tucson Water crews were working to repair a water line break at North Columbus Boulevard at East Speedway.
Crews were expected to fix the line by 9:30 p.m., and motorists should avoid the area if possible until the work is completed, said Fernando Molina, a Tucson Water spokesman.
Columbus southbound from Speedway is closed, and the northbound left turn lane onto westbound Speedway is closed, Molina said.
About 30 area businesses were affected and Tucson Water officials have notified the businesses.
Molina asks motorists who can not avoid the area to exercise caution to help ensure the safety of workers.
The cause of the water line break is unknown. No further information was immediately available.