The search for a 23-year-old man who went missing while swimming near Great Falls Monday night is underway.
Montgomery County Fire and Rescue and U.S. Park Police units are returning to the area of the Potomac River where the unidentified swimmer went under just before 8:30 p.m. Monday night.
Witnesses told authorities that they and the missing man were wading on the Virginia side of the Potomac near Great Falls when the victim swam into an area over his head. He then began to struggle and wend under.
Authorities say the man briefly resurfaced a short way downstream, but then went back under and didn't come back up.
Rescuers from the Park Police, Montgomery County and Fairfax County suspended their search due to darkness Monday night.
Searchers are expected to resume their effort through the morning Tuesday and then later in the afternoon.
If the man drowned, it would mark the fourth drowning this year in the Potomac Gorge in Great Falls National Park.
ABC7's Kevin Lewis contributed to this report.