Photo: CTV

Burnaby RCMP say a senior citizen suffered what they describe as life-altering injuries during an attack in a Metro Vancouver park.

Police say the unnamed 73-year-old man was walking in Central Park just after 9 p.m. on Sunday evening when he was assaulted.

No arrests have been made but an RCMP news release says witnesses report seeing a young man in the area during the time the assault is believed to have occurred.

He's believed to be between the ages of 14 and 18 with a slim build and just under six feet tall.

He was wearing a white T-shirt, blue jeans, white shoes and possibly a red cap when he was last seen running toward a nearby SkyTrain station.

Cpl. Michael Kalanj says the senior was initially thought to have been only slightly hurt, but his injuries have been reassessed and are much more serious.

Thirteen-year-old Burnaby resident Marrisa Shen was found murdered in the same park one year ago this week.

Police have said no arrests have been made in that case, despite a continuing RCMP investigation that has included a review of about 1,000 hours of video and checks of at least as many people.

Shen was last seen at a Tim Hortons restaurant near her home and at Central Park around 6 p.m. on July 18.

Her body was found in the park in the early hours of July 19, just hours after her mother had reported her missing.