LYNNWOOD, Wash. -- A 28-year-old Snohomish County man died in a motorcycle accident on Wednesday, according to the sheriff's office.

Sheriff's spokesperson Rebecca Hover said the man was riding a 2006 Harley Davidson when he crashed onto a concrete sign post at the intersection of 140th Street SW and 64th Avenue just before 8 p.m.

The motorcyclist was not wearing a helmet at the time of the crash, Hover said. The man, whose name is not known, died at the scene.

The cause of the crash is not known.

The investigation is ongoing.