Police released a description of a man who came up behind a woman in Bear Creek Park and struck her on the head with what is believed to be a metal pipe around 7 a.m. Thursday.

Police said the man is thin, white or Hispanic, and was wearing a white tank top, black sweat pants and had a black backpack.

The woman was attacked from behind while in the south side of the park near Beta Loop and Sirius Drive. The suspect fled after seeing a nearby bystander.

Police searched the area but were unable to find the attacker.

The woman was treated at a local hospital for serious, but nonlife-threatening injuries.

Lt. Dave Gilman cautioned people against staring at their cellphones and to be aware of their surroundings, especially when by themselves or in isolated areas.