NEW YORK — An explosion on a boat carrying raw sewage that was docked on the Hudson River in New York City killed a longtime city employee Saturday, authorities said.

Another worker on the city-owned Hunts Point vessel was injured and taken to the hospital after the blast around 10:30 a.m. near the North River Wastewater Treatment Plant, according to city Fire Department Deputy Assistant Chief David Simms. A third worker refused medical treatment.

The cause of the explosion was under investigation, but New York City Mayor Eric ams said in statement that criminal intent was not suspected. The men on the boat, which takes raw sewage from the city to be treated, were doing work involving a flame or sparks when the explosion occurred, the U.S. Coast Guard said on social media.

First responders found a 59-year-old man unconscious in the river, New York police said, and he was declared dead at the scene.

The man had been a longtime employee of the city’s Department of Environmental Protection. His name has not been released, but the mayor said he was “a devoted public servant who gave 33 years of service to the New York City, and our hearts go out to his family, friends, and colleagues during this painful time.”

The blast spread raw sewage over the deck of the boat, and firefighters and other first responders had to be decontaminated, Simms said. DEP said there did not appear to be any environmental impacts following the explosion.