A Sun Van driver was on the job Monday when he was arrested for driving under the influence, a police official said.

Michael Ross, 48, was cited for “basic DUI,” indicating he was “impaired to the slightest degree,” said Sgt. Maria Hawke, spokeswoman for the Tucson Police Department. However, charges may be added once tests determine the level of his blood-alcohol content.

Ross was stopped in the 7700 block of East Speedway west of North Pantano Road, at about 4:45 p.m. He was released into the custody of his supervisor and another driver took over his shift, Hawke said.

Two or three passengers were in the van at the time Ross was stopped and several others were in the process of boarding, said Michele Joseph, spokeswoman for Sun Tran and Sun Van.

The mother of a Sun Van passenger noticed the driver “seemed a little off and (she) thought he smelled of alcohol” when he came to pick up her child, so she called 911, Hawke said.

Sun Van provides transportation for people unable to use Sun Tran’s fixed route service because of a disability, according to its website. Sun Van provides more than 400,000 passenger trips each year.

Per company policy, Ross “was suspended pending further investigation,” Joseph said.