After three people were injured in two shark attacks off the Florida Panhandle, authorities are increasing their sea patrols

Authorities patrol the sea with boats and warn swimmers about sharks this weekend along Florida’s Gulf Coast, where a woman and two teenagers were injured in two separate shark attacks on Friday.

Due to the attacks off the beaches of the Florida Panhandle, authorities temporarily closed several beaches to swimmers on Friday. The beaches reopened on Saturday with flags warning of the great danger.

“All I can say is that these incidents are very rare,” said Demian Chapman, scientist and director of the Center for Shark Research at the Mote Marine Laboratory and Aquarium in Sarasota, Florida.

“It is even rarer that two events involving three people occur on the same day,” he told the Associated Press on Saturday. “The probability of that happening is astronomically low.”

In Walton County, the sheriff’s office, fire department and state conservation agency worked together to patrol the water with boats and the shore with vehicles, the South Walton Fire District said in an update Saturday. Both of Friday’s attacks occurred in Walton County.

“Please swim carefully today, respect the Gulf, stay hydrated and look after your loved ones,” the fire department said on social media.

On Saturday, red and purple flags were used to warn swimmers of the dangers.

“Purple flags indicate the presence of dangerous marine life and single red flags indicate a high danger level,” the Bay County Sheriff’s Office said in a social media post Saturday.

At this time of year, small fish are found in schools near the shore, which may have contributed to the attacks, the Bay County Sheriff’s Office said.

The first attack occurred Friday afternoon when a woman was bitten by a shark near WaterSound Beach, the Walton County Sheriff’s Office said. She suffered severe injuries to her abdomen and arm, and part of her arm had to be amputated, South Walton Fire Chief Ryan Crawford said at a news conference. She was flown to a trauma center.

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

Two teenagers 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 women had significant injuries to her thigh and hand,” firefighters said in an update. She was flown to a trauma center. The other teen had what officials described as minor injuries to a foot.

The two teenagers are from Mountain Brook, Alabama, a suburb of Birmingham, Mountain Brook City Manager Sam Gaston told news site Al.com.

There is no way to determine whether one or two sharks were involved in Friday’s attacks, but there are more sharks in the Gulf of Mexico than in recent years, Chapman said.

“After years of overfishing, shark numbers in the Gulf have definitely recovered,” he said. “After being severely depleted, they’re back out there, so to speak.”

The timing of the attacks — mid-afternoon — was also unusual, said Walton County Sheriff Michael Adkinson. Sheriff’s officials often warn people to be on the lookout for sharks early in the morning and at dusk, which are typical feeding times, he noted.

On Saturday, Walton County Sheriff’s officers patrolling the waters by boat spotted a 14-foot hammerhead shark near Santa Rosa Beach, which they said is not unusual. Sheriff’s officials say they do not know what type of shark attacked the swimmers on Friday.

“We want to reiterate that sharks are always present in the Gulf,” the sheriff’s office said in a social media post Saturday. “Swimmers and beachgoers should exercise caution while swimming and be aware of their surroundings.”

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

Experts say shark attacks are rare. According to the University of Florida’s International Shark Attack File, there were 69 unprovoked bites worldwide last year, 10 of which were fatal. That’s more than the recent average of six deaths per year.