WATCH: Hammerhead Shark Hunts Along Nantucket Beach

There were more than 20 shark fin sightings along the south shore of Nantucket over the weekend, prompting town lifeguards to close numerous beaches for extended periods of time.

The closures, required by the town's protocol for confirmed shark sightings, began early last Thursday morning and continued on Friday. But the bulk of the sightings came on Saturday and Sunday along the south shore.

And the one everyone has been talking about - a hammerhead shark at Ladies Beach - was filmed by several people as it was hunting for fish close to shore, and at one point got rolled over by wave.

Usually found in tropical waters, hammerhead sharks are rarely seen so close to the island, let alone in the surf break along Nantucket's south shore.

Watch the incredible videos above of the encounter shared with the Current by Annabel Taylor and Lisa Larson, who were at Ladies Beach on Sunday.