CHICAGO (CBS) — A semi truck fatally struck a man on the Dan Ryan Expressway on Tuesday morning, Illinois State Police said.

The man was struck about 9:40 a.m. in the northbound lanes at 83rd Street.

It is unknown why the man, who was pronounced dead on the scene, was on the expressway.

The three right northbound lanes and the 83rd Street entrance ramp to the expressway were closed as of 10:30 a.m.

Further details were not immediately available.