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

The shooting took place early on Sunday at Willie’s Bar and Grill on St Helena Island, 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 gunshots,” the Beaufort County Sheriff’s Office said in a statement on social media.

“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,” the statement said.