City lifeguards will keep shark warning signs up at Makaha Beach until at least Friday morning as a precautionary measure in the aftermath of a shark attack Wednesday afternoon in waters near the shoreline.

A 51 year-old woman who had been swimming about 250 yards offshore sustained a large gash across her right arm, shoulder and torso in the attack. Lifeguards, assisted by surfers, brought the swimmer to shore at about 2:30 p.m. Paramedics treated the injured woman on the beach and transported her to a trauma center in serious condition.

After the rescue, lifeguards posted shark warning signs and cleared the water. The beach was reassessed today, with lifeguards patrolling of the area. No shark has been spotted today in the Makaha Beach area, said Shayne Enright, spokeswoman for the city’s Emergency Medical Services.

The incident marked the fifth shark attack in the state this year, and the first on Oahu in 2016. Three occurred on Maui and one on Kauai this year, and none involved a fatal injury.

The last shark attack at Makaha Beach occurred in late October when a boy on a bodyboard was bitten on the leg about 50 to 60 feet from shore.