The incident happened about 10:35 a.m. along southbound I-5 near the 88th Street NE exit, said trooper Mark Francis.
The bus had pulled over and someone called 911 because the man was being "disorderly," Francis said.
A motorcycle trooper pulled up behind the bus. The man went prone on the ground outside, Francis said.
The man then jumped up and attacked the trooper, who suffered a black eye and a bloody nose, Francis said.
The trooper attempted to shock the man with an electronic stun gun but it wasn't immediately clear if the man was hit, Francis said. The man eventually was arrested and taken to a local hospital to be looked over.
Traffic was not affected during the incident, which remains under investigation.
Additional details weren't immediately available Monday.
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