The Coast Guard was searching for four divers some 50 miles south of Cape Fear, North Carolina, officials said Sunday, and the search was to continue into Monday morning.

The Coast Guard said it was notified that the four men were diving from a pleasure craft called Big Bill’s approximately 63 miles east of Myrtle Beach, South Carolina near noon on Sunday and hadn’t resurfaced.

Numerous aircraft and surface vessels were involved in the search, including an MH-60 Jayhawk helicopter and HC-130 Hercules aircraft.