Portland Police are investigating a series of recent assaults in the city to determine if they’re connected.

David Singer with Portland PD says they’re investigating another assault in Fort Sumner Park that happened at 10:00 p.m. Wednesday. They said the victim, a 33-year-old man, was sitting on a park bench when he was struck from behind in the head with a blunt object.

The victim took himself to the hospital and was treated and released.

He described the suspect as a male with dark complexion wearing a white t-shirt.

The incident is similar to three attacks in recent days, in which all of the victims were women.

Police say they’re confident that these incidents are not connected to an assault that happened in October, in which the suspect was identified but the victim chose not to pursue charges.

Police say they’re stepping up patrols in areas where attacks have happened and are asking for residents to report any suspicious activity.