LUMBERTON, N.C. — With helicopters overseeing the rescue operation from above, volunteer firefighters turned their military-surplus truck with 4-foot tires into the dark flood waters, cruising past a mortuary, grocery and homes in part of this city that flooded when a river swollen by Hurricane Matthew overflowed.

They joined U.S. Marshals and water rescue teams from as far away as New York and New Jersey focused Monday on retrieving about 1,500 residents who were trapped when the Lumber River unexpectedly rushed out of its banks, up their stairways and into buildings.

The half-dozen men from the nearby town of Rayham spent about 10 hours Monday at the rescue work aboard their truck — usually used for fighting brush fires in this swampy, rural southeast corner of North Carolina. They primarily located and ferried to safety rescued residents in inflated dinghies or bass boats to meet the truck on the neighborhood’s main street.

“We’ve got it nowhere near this bad,” said Jimmy Hunt Jr., son of the chief of the volunteer fire department in Rayham.

The rescue teams were expected to be back at work across eastern North Carolina on Tuesday as the deluge rolled downstream toward the Atlantic Ocean. At least three rivers were forecast to reach record levels, some not cresting until Friday.

Hurricane Matthew killed more than 500 people in Haiti and at least 23 in the U.S. — nearly half of them in North Carolina. At least three people were missing.

The full extent of the disaster in North Carolina was still unclear, but it appeared that thousands of homes were damaged, and more were in danger of flooding.