Police said an 18-year-old man died a hero while trying to rescue four passengers in a car that plunged off the banks of a Delaware canal on Sunday morning.

He got one of the passengers safely to shore, but two others were later found dead, and a fourth was still missing Sunday night, police said.

The man was driving the car when it fell into the Chesapeake and Delaware Canal in Middletown, about 20 miles southwest of Wilmington, at around 9:41 a.m., said Master Cpl. Michael Austin, a spokesman for the Delaware State Police.

The man, who hadn't been identified, was able to help a 16-year-old girl swim to shore — then he dived back in the water to try to save three boys who were also in the car.

He never made it back, and his body was recovered from the water a short time later, authorities said.

"He was a hero and tried to do everything he could to help the remaining passengers in that vehicle," Austin said.

Dive teams found the car at around 3 p.m., and after it was removed from the water, they discovered two boys, ages 16 and 12, who were pronounced dead, police said. A 6-year-old boy remained missing Sunday night.

"Our thoughts and prayers go out to a family whose lives were changed forever today, unfortunately," he said.