Winnipeg police are “scratching their heads” over why a 19-year-old woman allegedly abducted a baby girl from a house party and brutally beat the child's head against a city sidewalk.

Nikita Solange Eaglestick was charged Wednesday with attempted murder, abduction and aggravated assault while the 14-month-old baby continued to recover in hospital.

Constable Jason Michalyshen said police still don't understand why the little girl, identified by family as Vanessa, was attacked.

“That is something that we're all kind of scratching our heads right now to try and figure out,” he said.

“Our investigators spent the majority of (Tuesday) interviewing witnesses, individuals that may possess valuable information with regards to the investigation. We're going to be continuing with that investigation by interviewing individuals that may help us find out some of those answers.”

“As far as a motive or a reason as to why this child was attacked in the manner that she was, is something that we need to figure out yet.”

Police say the mother was at a house party in the area and her baby daughter was asleep. People were drinking and, at some point, the baby was taken from the party.

“Once removed, the serious assault occurred,” Const. Michalyshen said.

Police didn't get any calls about a missing baby and were only notified when a witness saw a woman banging a child's head into the sidewalk. The suspect was arrested a few blocks away.

There is no relationship between the alleged assailant, who recently lived in northern Manitoba, and the girl's mother, making the incident even more baffling, Const. Michalyshen said.

“This impacts everybody negatively,” he said. “We certainly want to get to the root of the issue as to why this individual was involved in this type of an assault.”

The Winnipeg Regional Health Authority said it couldn't comment on the baby's condition “given the circumstances.” Const. Michalyshen said the child's condition has been upgraded from critical to stable.

“Right now the child is still in hospital recovering from serious injuries, upper body injuries,” he said. “The child is in stable condition, on the road to recovery. As far as future, long-term injuries, that's not something I can speculate.”

Police are now working with Child and Family Services to “make sure that all children involved either directly or indirectly are cared for in a proper manner,” Const. Michalyshen said.

The witness, 18-year-old Tyler Bilsborrow, has been called a hero for interrupting the attack.

Mr. Bilsborrow stepped outside his family's home to smoke in the pre-dawn hours Tuesday, when he heard screaming nearby.

He walked around the corner to see a woman sitting on the pavement, holding the baby by the neck and slamming the child's head down.

When he approached, he said the woman abandoned the child and ran away.

“It was completely covered in blood. It looked pretty bad. The nose looked like it was broken, all swollen. (The baby) could barely open it eyes. From head to toe, just covered in blood,” Mr. Bilsborrow said Tuesday.

The child was wearing only a T-shirt and a diaper, he said.

Vanessa's grandmother has said the child's mother, Daisy Houle, is devastated.