Two men in their 50s died after a motor vehicle collision on the H-1 freeway near the airport Sunday night.

Honolulu police said at about 9:25 p.m., a driver rear-ended a three-wheeled motorcycle, also known as a slingshot, on the H-1 freeway before the Dillingham Boulevard exit.

The slingshot was driven by a 56-year-old man, who remained in the cockpit after the collision. His passenger, a 55-year-old man, was ejected onto the highway.

Both men were pronounced dead at the scene, police said. Neither were wearing helmets.

The driver, a 37-year-old man, was treated for multiple injuries by Honolulu Emergency Medical Services, and taken to the hospital in serious condition.

Police said it remains unknown at this time if speed, drugs, or alcohol are factors in the collision.

Police said these were the 25th and 26th traffic fatalities on Oahu this year.

An investigation is ongoing. Anyone with information should contact the HPD Traffic Division at 808-723-3413.