WASHINGTON — A water rescue operation has been suspended for the night at the Triadelphia Reservoir at the Montgomery County-Howard County border.

A 19-year-old man swam in the reservoir with a group before 6 p.m. Wednesday and went missing. Witnesses say he went underwater and did not come up for air.

Swimming in that reservoir is not allowed.

“It’s unlikely that it’s a rescue operation at this point,” says Montgomery County Fire and Rescue spokesman Pete Piringer, “but we’re holding out.”

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