The cause of the explosion was under investigation. The men on the boat were doing work involving a flame or sparks when the explosion occurred, the U.S. Coast Guard said on social media.
The boat takes raw sewage to be treated, Simms said. The explosion happened near the North River Wastewater Treatment Plant.
First responders answering a 911 call found a 59-year-old man unconscious in the river, and he was declared dead at the scene, New York police said.
His name has not been released, but the New York City Department of Environmental Protection said the man had worked for the agency for 33 years. DEP Commissioner Rohit T. Aggarwala described the man in a statement as "a valued and experienced member” of the agency.
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.
___
This story has been updated to correct the number of injured employees who were taken to the hospital based on new information from authorities. One worker was transported, not two.