Two men on a party bus were shot and wounded early Saturday on the I-94 Expressway just outside of Chicago.

The shooting happened about 4:30 a.m. on the expressway near 147th Street, according to Illinois State police.

Shots were fired at the bus from inside another vehicle and wounded two men, police said.

About 20 people were on the bus traveling from a rap performance, according to CBS2. A 20-year-old man was struck in his hip, and another man was grazed in his ear. They were taken to Christ Medical Center in Oak Lawn with wounds that were not life-threatening.

An investigation was underway, police said. Additional details were not released.