CHICAGO (CBS) — Illinois State Police were investigating an overnight shooting on the Kennedy Expressway.

Police said the victim called 911 around 11 p.m. Wednesday, reporting he had been shot on the Kennedy in the inbound lanes near Addison.

The 28-year-old man drove himself to Swedish Covenant Hospital to be treated for a gunshot wound to the torso. He later was transferred to Stroger Hospital. Police said the injury was not believed to be life-threatening.

State troopers closed off the inbound lanes of the Kennedy between Addison and Kimball after the shooting to search for evidence, but they did not find any shell casings.

Investigators did not know if other vehicles were involved, or how the shooting happened.

No one was in custody Thursday morning.