SEACREST, Florida (AP) — Authorities are warning of shark dangers this weekend along Florida's Gulf Coast, where three people were hurt in two separate shark attacks on Friday.

The attacks off beaches in the Florida Panhandle led authorities to temporarily close beaches to swimmers in Walton County on Friday. Officials said they were evaluating conditions and safety measures to be taken for the rest of the weekend.

Small fish are traveling in schools near the shore this time of year, which might have been a contributing factor in the attacks, the Bay County Sheriff's Office said in a statement.

Some beaches on Saturday had red flags as well as purple ones flying to warn swimmers.

“Purple Flags indicate the presence of dangerous marine life and single red flags indicate high hazard conditions,” the Bay County Sheriff's Office said in a social media post on Saturday.

Both of Friday's attacks happened in Walton County, though other counties are taking precautions as well.

The first attack happened Friday afternoon when a woman was bitten by a shark near WaterSound Beach, the Walton County Sheriff's Office said. She had critical injuries on her hip and lower left arm and was flown to a trauma center, authorities said.

Less than two hours later, firefighters responded to another beach about 4 miles (6.4 kilometers) east of the first attack “following multiple reports of a teenager injured by a shark,” the sheriff’s office said.

Two teenage girls were in waist-deep water with a group of friends when they were attacked, the South Walton Fire District said.

“When lifeguards and deputies arrived on scene, they found one of the females had significant injuries to the upper leg and one hand,” fire officials said in an update. She was flown to a trauma center. The other teen had what officials described as minor injuries on one of her feet.

Also Friday, in Hawaii, a woman was seriously injured in an apparent shark attack in the waters off the island of Oahu, officials said.

Shark attacks are rare, according to experts.

There were 69 unprovoked bites last year worldwide, and 10 of those were fatal, according to the University of Florida’s International Shark Attack File. That was higher than the recent average of six deaths per year.