Ottawa police are hunting for a man after a woman reported being sexually assaulted on Saturday.

Police say the 25-year-old was walking along the McKenzie King Bridge by downtown Ottawa's Rideau Centre when she was attacked from behind.

She reports the unknown man touched her inappropriately and took off. The incident happened around 2:30 a.m.

He is described as 5'11", 175 lbs, and wearing all black clothing -- including a black mask.

Anyone with information is asked to contact the Ottawa Police Service Sexual Assault/Child Abuse Unit at 613-236-1222 ext: 5944 or Phone Crime Stoppers at 613-233-8477 (TIPS) or toll free at 1-800-222-8477.