State police report that an accident on southbound Interstate 81 in Montgomery County is causing traffic delays.

Police said the left lane is closed near the accident at mile marker 128 near Elliston. Traffic is backed up four miles near the site.

The accident involved two motorcyclists who inadvertantly fell in an attempt to lower their speed, said state police spokesman Sgt. Rob Carpentieri.

He said the motorcyclists fell around a construction site near the Ironto exit.

"It's like a domino affect," Carpentieri said of the crash. "These motorcycles tried to slow down as cars ahead of them did."

Carpentieri said one of motorcyclists, Tyrone Walker, was taken to the New River Valley Medical Center with non-life threatening injuries. The other rider, Harris Grant, was uninjured, Carpentieri said.