A Valley Metro bus caught fire Tuesday morning on the Red Mountain stretch of Loop 202 near Country Club Drive and McKellips Road.
Mesa Fire Department crews responded to the scene with two engines and a ladder truck about 9:45 a.m. and reported no injuries.
"We had a lot of fire when we got here," Mesa fire Capt. Paul Simley said.
Eastbound lanes of the freeway were backed up as firefighters worked at the scene. A single eastbound lane reopened about 10:30 a.m.
Simley said no passengers were on the bus at the time of the fire. He said the driver had just finished his morning route and was bringing the vehicle to a Valley Metro bus yard when the engine caught fire.
The driver pulled the bus onto the HOV lane and exited the vehicle, which runs on compressed natural gas. Simley said fire crews will leave the bus in the HOV lane while the engine cools down.
"The reason why we're waiting is to let the gas system stabilize," Simley said.
Valley Metro officials were at the scene by 10:30 a.m. to assess the situation.