Police have released surveillance video and a photo of a man who approached a woman from behind and struck her in the head earlier this week, and the case is similar to three unsolved attacks in 2010 and 2011.

The latest case happened on Tuesday at about 2 p.m., police said. The victim, a 27-year-old woman, was walking along Bayview Road near a roundabout at Burnside Avenue.

Suspect photo Hintonburg attack woman hit head struck

At the time of the most recent attack, Ottawa police released this photo of the suspect. (Ottawa police handout)

"She was struck in the head with an object, which caused her to fall to the ground," police wrote in a media release.

The suspect ran away in the opposite direction.

The victim suffered minor injuries and was taken to hospital in an ambulance.

The man is described as having light brown skin, 30 to 40 years old, standing at five feet six inches with a thin to medium build. He was wearing a black jacket, possibly leather, and a greenish baseball cap and black sneakers.

Unprovoked attack similar to 3 unsolved cases in 2010, 2011

Composite sketch suspect attacks women Centretown Hintonburg 2010 2011

In January 2011, Ottawa police released this composite sketch of a suspect in three separate unprovoked attacks on women in Centretown and Hintonburg. (Ottawa police handout)

Tuesday's attack is very similar to three attacks on women in Centretown and Hintonburg that police warned the public about in 2010 and 2011. A composite sketch of the suspect in all three cases was released by police.

The first incident happened on Dec. 11, 2010, a Saturday.

At about 1 p.m., a 45-year-old woman was walking along Spencer Street near Hamilton Avenue North in Hintonburg when she was struck by an unknown object on the back of the head by an unknown man.

She suffered a concussion and fell to the ground, police said, and was later taken to hospital. The suspect ran away in the opposite direction.

Investigators had no witnesses, no leads and no suspects, and the case remains unsolved.

2nd incident later that day

The second incident happened later that same afternoon, just half an hour later, at the intersection of Albert Street and City Centre Avenue.

A 58-year-old woman was walking along Albert Street when she was struck on the back of the head by an unknown man. In this case, the woman didn't know if she'd been hit with an object or the man's fist.

Again, the man ran away in the opposite direction. The victim managed to walk home and later went to hospital to have her injuries assessed.

There were no witnesses, no leads, no suspects and no arrests.

3rd attack less than a month later

The third incident happened less than a month later on Jan. 4, 2011, a Tuesday.

Just after 5 p.m., a 49-year-old woman was walking along Gilmour Street near Bay Street in Centretown when she was struck on the back of the head, again with an unknown object held by an unknown man.

Once again, the suspect ran away in the opposite direction.

While there were witnesses this time, no suspects were ever identified and no arrests were made. The case remains unsolved.

Police say they're investigating the possibility of a link between the unsolved cases and the most recent attack this week.

Anyone with information about the Tuesday attack asked to call central district investigators at 613-236-1222, ext. 5166, or Crime Stoppers at 613-233-8477 (TIPS) — toll free at 1-800-222-8477.