CALGARY -- Police are investigating a second, seemingly random assault in a Calgary park over the weekend, but say the two don't appear to be connected.

A man in his 50s was walking on a path in Fish Creek Provincial Park about 10:15 a.m. Saturday, east of Macleod Trail and south of Canyon Meadows Drive S.E., when he was struck from behind by an unknown male.

The suspect fled after taking some personal items belonging to the victim, who was taken to hospital in serious condition.

The suspect is described as being male, between 40 and 50 years old, with brown skin, black hair and a medium build. He was wearing a black top with white dots and black pants.

Police say they don't have any information linking the attack to the random stabbing of a teenager, also in a Calgary park, on Saturday evening.

The teen and his mother were walking in an off-leash dog park near 110th Avenue and 14th Street S.W. about 7:50 p.m. when they came across a man they didn't know and the boy was stabbed.

The suspect in that case was described as being a male between the ages of 40 and 50 years old who was wearing dark clothing and a three-quarter-length jacket with reflective markings.

"The random nature of the two incidents that occurred this weekend is extremely concerning to us," said Staff Sgt. Jeff MacQueen.

At a press briefing Monday evening, MacQueen reiterated that the two incidents weren't related.

"It's important to remember these sometimes happen in the same day," he said. "However, they are unrelated."

MacQueen pointed to different physical descriptions of the suspect in each assault, and different motives as well.

"In the one yesterday, robbery wasn't a motive in that," he said. "And the physical description was different. Yesterday, (the suspect) was(described as) a caucasian male, while this (the Fish Creek assault) , the suspect was (described as) a brown-skinned male, and robbery was a motive."

MacQueen said the Fish Creek victim was doing better physically, as was the 15-year-old victim of the stabbing.

Officers have spoken to several witnesses and reviewed CCTV footage from the area, however are still seeking assistance from the public.

Residents in the area who have security cameras are asked to check their recordings for anything suspicious.

Anyone with information is asked to call police at 403-266-1234 or Crime Stoppers at 1-800-222-8477.