St. Paul police are asking for the public’s help finding an armed man who forced a woman into the back of a minivan Tuesday night and sexually assaulted her.

The woman did not know the suspect, who remains at large.

Officers on patrol happened upon the woman, who was unclothed, about 11:50 p.m. as she ran across Case Ave. E. Officers learned that she had just been assaulted and released nearby by her attacker.

“She was screaming and crying and very distraught,” said police spokesman Steve Linders.

The woman was taken to Regions Hospital.

According to police, the woman said she was walking on Payne Avenue near Geranium Avenue about 11:30 p.m. when a tan minivan pulled up next to her. The male driver asked for her name, and she ignored him.

A short time later, she heard a noise behind her on the same street and turned around. She saw a man about 6 feet tall, with a medium build, wearing a black ski mask, a worn baseball cap, black pants and a light-colored jacket over a sweatshirt.

The man motioned with his head to a small, black semiautomatic handgun in his hand, Linders said.

The man told her not to scream and threatened harm if she did not follow his instructions. He forced the woman to walk to the tan minivan parked nearby on Geranium Avenue between Payne Avenue and Greenbrier Street.

“He did threaten her several times,” Linders said.

The suspect assaulted the woman, drove her about a block and told her to get out and not look back at him, Linders said.

Anyone with information can call police at 651-266-5687.