Divers and other recovery personnel with the Maryland Department of Natural Resources Police and the Baltimore County Fire Department resumed searching for the man Wednesday morning after hours in the water near Martin State Airport on Tuesday.
Rescue crews were first called to the area about 4 p.m. Tuesday after a bystander noticed three people in the water, the Coast Guard said.
When Coast Guard crews arrived, two of the swimmers -- women who'd been separated from the boat they were on -- had been pulled from the water by people in another boat, the Coast Guard and local officials said.
The missing man, who'd gone into the water to help the other two, hadn't been located, the Coast Guard said.
A search and rescue operation involving the Baltimore County Police marine unit, Baltimore County Fire Department divers and the Maryland Department of Natural Resources began, the Coast Guard said.
That rescue operation was halted and turned into a recovery operation about 5:30 p.m., said Lt. Jay Ringgold, a Baltimore County fire spokesman.
The recovery operation was ended about 8:15 p.m., before being resumed Wednesday morning, Albert said.
Albert said there are tides in the water where the man went missing, but drowning victims' bodies generally sink and stay in the general vicinity of where the drowning occurred for some time. Bodies only move with the tide after gasses in the body build up and it rises to the surface, he said.
The man had not been identified as of late Wednesday.