MILWAUKEE (CBS 58) -- The Milwaukee County Sheriff's Office is investigating a serious crash involving a motorcycle and a highway attenuator on I-43 northbound at the Marquette Interchange.

Deputies and emergency crews from the Milwaukee Fire Department and Bell Ambulance responded at around 1:36 a.m. Wednesday, Sept. 16, according to the sheriff's office.

The rider, described as a man in his mid-30s, suffered serious injuries.

The sheriff's office Crash Reconstruction Unit has been deployed to the scene, and the freeway remains completely closed at that location for the investigation. The cause of the crash is being investigated, and updates on the rider's condition and when lanes will reopen are expected as more information becomes available.