A mass shooting at a crowded bar on an idyllic US island has left four people dead and at least 20 injured, officials say.

The shooting occurred early on Sunday (late on Sunday AEDT) at Willie’s Bar and Grill on St Helena Island in South Carolina, officials said.

A large crowd was at the scene when sheriff’s deputies arrived and found several people suffering from gunshot wounds.

“Multiple victims and witnesses ran to the nearby businesses and properties seeking shelter from the gun shots,” the Beaufort County Sheriff’s Office said in a statement on the social media platform X.

“This is a tragic and difficult incident for everyone. We ask for your patience as we continue to investigate this incident. Our thoughts are with all of the victims and their loved ones.”

Four people were found dead at the scene, and at least 20 other people were injured. Among the injured, four were in critical condition at area hospitals.

The victims’ identities were not released.