Worried parent called police.

A North Dakota school bus driver has been charged with drunken driving after a worried parent called police.

Thomas Griak of Lincoln faces a charge of driving a commercial vehicle under the influence. Bismarck Police Deputy Chief Dan Donlin says the 41-year-old Griak was arrested after he'd finished his route taking children to the Bismarck Public Schools' early education program.

Drivers of commercial vehicles have a lower allowable blood-alcohol concentration. The legal limit to drive a commercial vehicle, such as a school bus, is .04 percent. The limit for drivers with standard licenses is .08 percent.

Donlin tells the Bismarck Tribune (http://bit.ly/O62Csd) that Griak was arrested based on his mannerisms and a breath test.

Schools Human Resources Director Lisa Kudelka says that Griak is on leave without pay.