A man was injured Saturday afternoon when his 2008 Harley-Davidson crashed into a tree on Route 109 in Acton.

Dana Seaboyer, 56, of Kingston, New Hampshire, was wearing a helmet when his motorcycle left the road at 3:45 p.m. and hit a tree as he traveled east with several other motorcyclists, York County Sheriff William King said Sunday.

Seaboyer was treated at the scene by Acton Fire and Rescue before he was transported by helicopter to Maine Medical Center in Portland, where he was listed in serious condition Sunday night.

Portions of Route 109 were shut down for about 90 minutes.

The cause of the crash is under investigation, King said.