Troopers responded to the crash just before 9 p.m. Friday. The man was pronounced dead at the scene, police said. Authorities have not released his name, age or hometown, and it was not immediately clear why he was in the roadway.

The collision forced the closure of northbound I-15 at Craig Road, a busy stretch of freeway that carries traffic between the northern Las Vegas Valley and the resort corridor. State police said northbound traffic was being diverted onto the Craig Road off-ramp, and the on-ramp was also shut down while investigators worked the scene.

Police did not estimate how long the closure would last, saying only that the freeway would remain shut for an unknown period during the investigation. Motorists were urged to avoid the area and use alternate routes.

No further information about the circumstances of the crash, including the speed of the truck or whether impairment was suspected, was released Friday night. State police said the investigation is ongoing.

The death adds to a grim tally of fatal collisions on Southern Nevada freeways this year. Pedestrians struck on high-speed interchanges are among the most vulnerable road users, and safety advocates have long pressed for better lighting, signage and enforcement at freeway on- and off-ramps where people on foot sometimes end up.

Anyone with information about the crash is asked to contact Nevada State Police. This story will be updated as more details become available.