A man died late Thursday night after the vehicle he was driving veered off the eastbound lanes of H-1, rolled over on an embankment and crashed into a signpost, authorities said.

Honolulu Emergency Services said paramedics responded at 11:37 p.m. to a roll-over, single-vehicle crash after the H-1 Kaonohi overpass and found a man, who was about 50 years old, dead at the scene.

Officials with the Honolulu Police Department’s Vehicular Homicide Section said in a report that the man “was traveling eastbound on the H-1 Freeway, when for unknown reasons he veered right of the roadway, traveled up an embankment and collided into a metal signpost, partially ejecting the adult male onto the grassy embankment.”

The motorist was not wearing a seat belt, according to police, who said speed appears to be a factor. It is unknown if alcohol or drugs were involved.

Police did not immediately identity the victim nor the type of vehicle.

An EMS report said there were no witnesses.

Police closed three lanes of H-1 eastbound while they investigated the overnight crash.

This is Oahu’s 27th traffic fatality so far in 2023, compared with 23 at the same time last year, according to HPD.