The fire prompted environmental scrutiny across state lines, with the New Jersey Department of Environmental Protection saying it was tracking potential impacts to air quality, water quality, and ecological resources of the Delaware Bay estuary.

NEW CASTLE, Del. — A large fire erupted Tuesday morning aboard an unmanned barge loaded with scrap metal on the Delaware Bay and burned into the evening, drawing U.S. Coast Guard responders, fire departments from Philadelphia and Wilmington, Delaware, and environmental monitors from two states. No injuries were reported.

The U.S. Coast Guard received reports of the fire after 8 a.m. and dispatched a helicopter and two boats, said Petty Officer First Class Matthew West. Fire departments from Philadelphia and Wilmington also responded.

A tugboat was towing the unmanned barge when the fire broke out, West said. Coast Guard crews towed the barge to a position about 2 miles (3.2 kilometers) off Maurice River Cove in New Jersey to clear the threat from the main ship channel. Ship traffic on the bay was not affected, West said.

Hours after the initial report, the barge appeared stationary as boats on each side directed water cannons into the piles of burning metal, with smoke billowing from multiple fires aboard. The cause of the fire remained under investigation, West said.

The Delaware Emergency Management Agency said the barge was being moved to shallower water. The New Jersey Department of Environmental Protection said it was working with the Coast Guard and the New Jersey Office of Emergency Management and monitoring “for potential impacts to air quality as well as water quality and ecological resources of the Delaware Bay.”

The Delaware Bay is an estuary of the Delaware River, separating Delaware from New Jersey.