A 16-year-old boy is assisting police with their inquiries after a frightening random attack on a Queensland beach on Monday.

Police said they were called to Blacks Beach in Mackay, in the city’s north, about 12.20pm on Monday, where they found a 23-year-old woman with serious injuries.

She had sustained multiple stab wounds.

Police say preliminary information suggested the woman was sunbathing at the beach when she was confronted by a male she did not know. They allege he stabbed her multiple times in the neck and body with a knife before fleeing the scene.

“She was stabbed multiple times to her head, neck, arms and legs,” Detective Inspector Tom Armitt said.

“She’s then sought help and [gone] to a local construction site and received some help from the builders.

“It appears it’s a random attack.”

The woman ran to the nearby building site on Blacks Beach Road, where builders called paramedics.

She was taken to hospital in a serious condition. However, her injuries are believed to be non-life-threatening.

Queensland Police took the teenager into custody shortly after.