A major Tempe gas line ruptured Thursday, forcing officials to evacuate about 50 people from businesses and Arizona State University.
Fire officials responded to Rural Road south of University Drive about 9:45 a.m. after construction workers digging a trench caused a Southwest Gas line to rupture. Officials are investigating how the rupture occurred.
Southwest Gas was not readily available for comment.
"Gas is quite volatile," Tempe fire inspector Phil Rohe said. "You want to do everything that you can to not create any type of ignition source."
Firefighters are working to measure gas levels in the air, while Southwest Gas crews are clamping off the leak on the 4-inch diameter pipe, Rohe said. Police are assisting with traffic.
"It's a very large main gas line that serves Tempe," said Sgt. Dan Masters. "It will take several hours to repair, which could cause some challenges to students trying to get in and out."
The rupture did not cause any ASU classrooms to be evacuated but has caused traffic delays in an area already congested from light-rail construction and other projects.
Rural Road is closed from Rio Salado Parkway to Terrace Road, police said. Expect delays for a few hours.