An off-duty lifeguard spotted two sharks Friday afternoon at a Waimanalo beach.

Two sharks about 8 feet to 10 feet long were seen 30 to 50 yards offshore at about 2:15 p.m. in the area of Bellows Air Force Station, Shayne Enright, Emergency Services Department spokeswoman, said.

“The sharks were acting aggressively, thrashing in the water,” she said. 

The sharks were seen off the military side of Bellows, about a mile down the beach from the city’s lifeguard tower, she said.

 Lifeguards immediately cleared the water, and warning signs were posted.

The area will be reassessed at about 9 a.m. Saturday.