On Saturday, June 10, as boaters partied in the shallow waters around Alabama’s Robinson Island in the Gulf of Mexico, a half dozen hammerhead sharks cruised into their midst and sent the revelers scrambling. Boater Meredith Perry—whose fiance opted to remain in the water with the sharks—posted a video of the incident on Facebook that has since garnered 2.8 million views. See it for yourself below.

The video opens with the six hammerheads swimming in a tight formation toward one of the boats as two men in the water quickly climb back onto the vessel. The sharks then fan out and criss-cross between a circle of a dozen or more anchored boats loaded with excited onlookers.

“All of the sudden we started hearing people say shark, shark and then everybody getting on the boat,” Perry’s fiance Paul Hubble later told WLBT. “People thought they were fixing to get eaten alive or something…Everybody was climbing all over the boats. It was very dramatic to see.”

Hubble said there were six to eight sharks with him in the water during the encounter. He estimated one of them at ten feet long. “Two of them came up behind me and went around me,” he said. “They were feeding on something and doing their thing.”

Sensory organs in the hammerhead’s distinctive crown give them exceptional depth-perception and prey-detection abilities. They often hunt in shallow waters for stingray, squid, and octopus.  

Of the nine species of hammerhead, most are small and not considered a danger to humans. But the largest, the great hammerhead shark, can reach 20 feet and weigh 1,000 pounds or more. Still, very few attacks on humans have been recorded, and no human deaths have been attributed to the mallet-headed shark. 

Related: Land-Based Shark Angler Catches Giant 13-Foot Hammerhead off the Coast of Texas

Robinson Island is about 26 miles west of Pensacola, Florida, near the Alabama-Florida border. Hubble said he’s been boating there every weekend for years and has “never seen sharks come up like that.” In the video, the sharks stayed near the boats for about ten minutes before swimming off.