Two men disappeared in the Potomac River upstream from Washington on Sunday when their boat capsized, authorities said.

Lawrence W. Grey Jr., 62, of Brunswick, Md., and Robert Evonne Lee, 51, of Frederick, Md., had gone fishing near the Route 15 bridge between Loudoun County, Va., and Frederick County, Md., the Maryland Natural Resources Police said.

Divers were sent to the Point of Rocks, Md., area to search. The search was to resume Monday morning.

It was not known why the men’s boat capsized. Candy Thomson, a spokeswoman for Maryland’s Natural Resources Police, said the incident occurred in the morning, well before storms arrived.

In another incident, the body of an Anne Arundel County man who had jumped into the South River on Saturday was recovered Sunday, police said.

Thomson said Joseph Vincent Rossi of Edgewater had been in a rented motorboat with his wife and two children when a hat flew off and he tried to retrieve it.

Rossi’s wife was unable to stop the boat, Thomson said. Another boater helped get it stopped.

Friday was Rossi’s 47th birthday, Thomson said.