Divers are trying to recover the body of a man who officials believe drowned in Blue Lake, the Multnomah County Sheriff's Office said.

A man in his 20s and a woman jumped off a paddle boat in the lake at about 3 p.m. after the boat started to fill with water, said Sgt. Brandon White, a spokesman for the sheriff's office. The two tried to swim back toward the docks, but struggled in the water, he said.

A bystander saw them and went into the lake to help, White said. He got the woman to safety, but when he looked back, the man had disappeared under the water, White said.

Rescue teams searched the lake for the man, but were unable to find him.

The rescue mission transitioned to a recovery mission after about 45 minutes, meaning the man is presumed drowned, White said.

The woman did not appear to be injured, White said.

This story is developing and will be updated with more information as it becomes available.

-- The Oregonian/OregonLive