A 67-year-old man is presumed dead after he fell into the Potomac River in Virginia Friday, authorities said.

The victim’s name was not immediately released by D.C. police. The District is responsible for the river, from shore to shore, according to the D.C. fire department.

Vito Maggiolo, a spokesman for the fire department, said that around 7:40 a.m. Friday, the department received a 911 call from witnesses that a man, who had been trying to fish, fell off the rocks into the river along the Chain Bridge area.

Maggiolo said the man “went under and didn’t resurface.” Rescuers spent more than an hour searching for him by boat, helicopter and along the shoreline with a K-9 officer. Units from the Arlington County Police Department, Arlington County Fire Department, U.S. Park Police, D.C. police and D.C. fire department were involved in the search. By 9 a.m., Maggiolo said the operation had turned from a search to a recovery effort.

Maggiolo said it is an area where people fish but warned that the river is “much more dangerous than it sometimes appears.”

He said the man’s family described him as a “moderate swimmer.” The victim was not wearing a life jacket when he fell.

Maggiolo said the river is dangerous because someone can fall in and the “water can swirl you around and pull you under.” He urged people to stay on the shoreline.

“If you’re out on the slippery rocks and you fall into the river, the odds are that you’re going to be in grave danger and you’re going to lose your life.”