MISSOULA, Mont. (AP) — A 57-year-old northwestern Montana man is charged with flagging down a school bus and threatening the driver with a knife, apparently for driving too fast.

The Missoulian reports Duane Richard Tholen was arrested Friday and made an initial appearance in Lincoln County Justice Court Monday on two counts of assault with a weapon. His bail was set at $100,000.

Court records say a bus driver called 911 on Friday to report a man had flagged her down about seven miles south of Libby. The bus was carrying several children and an adult aide.

The driver says she opened the bus door, Tholen stepped on and started waving a knife around. The aide gave a similar account.

Charging documents say Tholen acknowledged flagging down the bus and confronting the driver about speeding near his residence, but denied any criminal behavior.