A group of onlookers at Sugarhouse Park watched as a Park City woman was sexually assaulted at knife-point, and then escaped from her assailant, who was later arrested, a police report said.

The woman, 36, was relaxing near a duck pond about 4:16 p.m. Wednesday when a man came from behind her and placed his hand over her mouth, telling her not to scream or she'd be hurt, the report said.She agreed not to scream and the man sat next to her, putting his arm around her and acting as if he knew her, the report said. The man then sexually assaulted the woman, who bit him in the hand, the report said.

He then pulled a 12-inch butcher knife from his pants and held the blade to the woman's throat, continuing to sexually assault her. When he laid the knife down, the woman grabbed the weapon and threw it, the report said.

The man got up to retrieve the knife and the woman said "I'm coming with you," but instead ran toward a police officer arriving near the scene, the report said.

The man was apprehended by the officer after a brief foot-chase. The weapon was found, and the woman identified the assailant for police.

Witnesses observed the incident, "wondering what was going on but (they) didn't want to interrupt anything," the report said.

Clay Henry Hopkins, 26, Salt Lake City, was booked into the county jail Wednesday on aggravated sexual assault and rape charges, according to jail records.