(NewsNation) — Three people are injured after gunshots were fired in the parking lot of Six Flags Great America on Sunday night.

Two of the people hurt at the park, located about an hour north of Chicago in Gurnee, Illinois, were transported to a local hospital, a park spokesperson said. The third person injured declined medical treatment.

The shots were fired from a vehicle that drove off immediately after the incident, the park said. Security guards and officers from the Gurnee Police Department substation responded immediately.

The park closed early and guests were evacuated, a park spokesperson told NewsNation.

Videos posted to social media showed large crowds leaving the park en masse, with some people trying to break through locked gates and climbing fences. Videos also showed people sheltering in place.

The shooting is under investigation.