A well-dressed "predator" posed as a truancy officer to lure a 15-year-old schoolgirl into his car - then drove to her Waitakere City home and sexually assaulted her.
The man told the girl before the attack that he had to take her home to ensure she wasn't wagging school.
Police were yesterday sending safety warnings to every school in Auckland and telling them of Tuesday's attack because they fear the man could strike again.
Detective Sergeant Steve Salton of Henderson police said the girl, from West Harbour, was heading home from school to study when the man approached her as she walked along Hobsonville Rd, near the Hobsonville RSA.
He said the man, wearing black dress pants and a tidy blue or black shirt, pulled up beside the girl in a white, older-model station wagon between 12.30pm and 1pm.
"He's told her that he was a truancy officer and to get in his car to ensure she's not wagging, and he's taken her to her home address where the assault's taken place.
"It was a calculated attack. He seemed to be very calm in his approach and may have some knowledge of the process related to truancy.
"Whether he knows somebody who is a truancy officer, I don't know, but it's a worrying aspect that he was so calm."
Mr Salton would not reveal details of the attack or the street it took place in, but said the man drove away from the girl's home at speed. The girl then called police.
The impact of the attack on the girl's end-of-year exams was yet to be known.
"She appears to be a very bright young girl and it was a very traumatic experience for her but she's holding up well."
Police are advising the public to be careful.
Yesterday, they conducted traffic stops in the area seeking clues to the man's identity. They plan to do more stops today.
"We don't know where he's come from or where he's going so it's best to cover all the bases," Mr Salton said.
"We are disturbed by the brazen attack. It's someone we don't need on the streets."
Secondary Principals Association president Peter Gall said the attack was "incredibly concerning".
"'It's quite sinister, planned, premeditated ... It's an absolutely terrible situation and points to the fact that young people need to follow all the advice they are given about keeping themselves safe on the way to school and on the way home from school."
The offender is described as a Pacific Island man, fat or stocky, and aged about 40.
He was about 165cm tall with very short hair.
It is the third predatory attack on young girls reported to Auckland police since Sunday. However, officers say the attempted abductions of two young girls in separate incidents in Grey Lynn on Sunday are not linked to the latest attack.
In the two Grey Lynn attacks, which occurred a short time apart, a man separately approached two girls, aged 13 and 10, grabbed them and tried to drag them away.
Both attacks occurred in the Richmond Rd, Brown St and Cockburn St areas.
The older girl, who had been walking her dog when she was grabbed from behind, screamed and alerted people, who helped her. The younger girl also broke free.