St. Paul police are looking for a suspect they believe attacked a 5-year-old girl at a bus stop Monday morning on the city's North End.

The incident was reported shortly after 8 a.m., when a bus driver for a charter school spotted her hiding behind a tree as he was picking up another student at the corner of Cook Avenue and Park Street, just off of Rice Street. The girl ran to the bus, and the driver called 911.

St. Paul police spokesperson Steve Linders described what officers found when they responded: "She was bleeding from the nose, she was bleeding from the mouth. Her face was swollen and it appeared that she had a broken nose. In addition, and perhaps most disturbingly, her pants and underwear were down around her right ankle. She was crying hysterically and unable to tell officers what had happened."

St. Paul police spokesman Steve Linders speaks at the scene of an assault of a 5-year-old girl on the North End on Monday morning. Tim Nelson | MPR News

She was taken by ambulance to Children's Hospital, examined, treated and then released to her family. Police are working with the Midwest Children's Resource Center and say the girl was interviewed about the incident Tuesday morning.

Linders said the nature of the assault isn't entirely clear, and police aren't sure if she was taken from her bus stop and returned. "She's 5 years old," said Linders at a press conference near where the girl was found. "She's traumatized, and she's doing the very best she can to share with us what happened. ... It's very possible that the victim was sexually assaulted. Right now, we just don't know. We're dealing with a 5 year old."

Linders said the suspect information the girl could offer was limited. The girl described him as a black male, a "big older boy" wearing a blue shirt and blue pants. The girl said she'd never seen him before.

"It's a crime involving a brutal assault of a 5-year-old child," Linders said. "It's a crime that makes us all sick to our stomach and has become the top priority of the St. Paul Police Department."

Police said the girl's mother reported dropping her off at her bus stop shortly before 8 a.m., that her bus arrived about 8:05 and didn't see her waiting as usual, and the charter school bus arrived less than five minutes later. Police think less than 15 minutes elapsed from the girl's drop off to the arrival of the second school bus and the 911 call.

Police are asking anyone who might have been in the area at the time or seen anything suspicious to call 651-266-5695.