A man was killed early Monday after being thrown from the back of a pickup truck on the H-1 freeway in Manoa and being hit by a van, police said.

The man was apparently involved in some dispute with the driver of the pickup truck, and the driver fled the scene, police said.

The crash occurred just before 4:15 a.m. in the westbound lanes of the freeway between the University Avenue onramp and the Wilder Avenue offramp.

Lt. Ben Moszkowicz of the Honolulu Police Department’s Traffic Division said an unknown male driver of a silver 2000 Toyota pickup truck was traveling westbound on the freeway when he struck a concrete barrier near Bingham Street.

A man described to be in his 30s was in the bed of the truck when he was thrown upon impact. He then struck a fence on top of the concrete barrier and landed on the roadway.

Moszkowicz said a white 2014 Nissan minivan operated by a 21-year-old man traveling in the same direction didn’t see the man lying on the roadway and struck him.

The man who was thrown from the pickup truck died at the scene.

Police said the Toyota pickup driver fled on foot and remained at large Monday. He was described as about 5-foot-10 to 5-foot-11 and 170 to 180 pounds. He was wearing a black hoodie and jeans at the time of the crash.

A 23-year-old woman, who was a passenger in the pickup truck, sustained a head injury in the crash and was treated and transported to a hospital by Emergency Medical Services, police said.

Police temporarily shut down the westbound lanes of the freeway to investigate.

Moszkowicz said police are continuing their investigation on what occurred prior to the crash and how the male passenger ended up in the bed of the pickup truck.

EMS said the truck was involved in a minor hit-and-run accident with a sedan, identified by police as a 2018 Toyota Camry, and the truck driver attempted to flee the scene. A passenger from the sedan jumped into the bed of the truck as it attempted to flee, according to EMS.

“I don’t believe it was a collision between the two vehicles,” Moszkowicz said. “I believe there was damage done, but I don’t believe it was (from) a collision.”

Speed on the part of the pickup truck driver may have been a factor in the crash. Police said it’s unclear at this time whether alcohol or drugs were involved.

This is the 20th traffic-related fatality on Oahu compared with 17 at the same time last year.

Anyone with information on the pickup driver is asked to call the Honolulu Police Department’s Traffic Division at 723-3413.