A 59-year-old man from Wilton was seriously injured Saturday afternoon when his motorcycle crashed on Forest Avenue in Portland.

Police said the crash occurred around 12:40 p.m. when Kevin Mullen lost control of his motorcycle near 835 Forest Ave.

Mullen was taken to Maine Medical Center, where he was listed in critical condition, a nursing supervisor said.

Police said Mullen’s motorcycle was the only vehicle involved in the crash and the cause is under investigation.

Forest Avenue was closed between Hartley and Walton streets for about 2½ hours, police said.