Parents in Newcastle have been urged to speak with their children about 'stranger danger' as detectives hunt a man responsible for the five-hour abduction and sexual assault of an 11-year-old girl.

Police patrols have been ramped up after the girl was grabbed from behind on Tuesday morning as she walked through Hudson Park in the suburb of Adamstown Heights.

She was then threatened with a knife, sexually assaulted and forced into a car.

The attacker then took the girl to bushland where she was subjected to further abuse before being released at the nearby Kotara Railway Station about 2.15pm - five hours after she was abducted.

Detective Chief Inspector Paul Jacob, from the sex crimes squad, said it was worrying the attack was committed in broad daylight.

"It is horrendous," he told reporters in Newcastle on Wednesday.

"It's our mission to get this person and remove him from the community as quickly as we possibly can."

Police were called when the girl walked 1.5 kilometres home before being taken to John Hunter Hospital for medical examination.

A crime scene was established at Hudson Park next to Belair Public School.

Det Jacob said the girl was doing "remarkably well" given what she endured.

"I am very thankful we have a very brave young woman who has been able to help us so valuably in our continuing inquiry," he said.

Local police stations are working with schools and community groups with increased patrols.

The NSW Department of Education provided a letter for schools to give to parents.

Kotara South Public School principal Susan Maxworthy said stranger danger talks had taken place in classrooms and assemblies.

"Parents can assist by reinforcing the stranger danger message with their child at home," the letter, sent on Wednesday, said.

An attached pamphlet provided safety tips for students, including to always identify safe places on the way home from school.

While the attacker attempted to hide part of his face with a hoodie, the girl was able to give detailed information about his appearance.

He's been described as "chubby" with short, dark, messy hair, brown staining on his teeth and wrinkles around his eyes and on his forehead.

He spoke in an Australian accent, and his hoodie was distinctive - dark grey and black with blue colouring at the waist level.

It's possible the car was red Holden Commodore, police said.

Det Jacob said police were eager to speak with anyone who may have dash cam footage of the area.