A shark attacked a seal just feet off Nauset Beach on Monday.
Video captured by a 7News viewer shows beachgoers clearing out of the water as they watch the seal try to get away from that shark.
Lifeguards can be seen running along the water line, telling witnesses to back away from the water and keep their distance from the animals.
Witnesses told 7News that lifeguards kept the beach closed after it was all over.
A crew is headed to the scene; stay with 7News for the latest.