Three days after an 11-year-old boy was plucked off a street and sexually assaulted in West Auckland, his attacker remains on the loose and a community is rallying to bring him to justice.

Police have received dozens of calls from the public about Thursday's abduction. Extra patrols will also be in place in the area in the coming days.

But the attacker - who has been described only as a man in a grey van - was last night still being hunted.

Detective Senior Sergeant Jason McIntosh said officers were supporting the boy, who is so traumatised it is unlikely police will be able to speak to him til mid-week.

The schoolboy had just got off a train at the Ranui Station shortly before 4pm Thursday when he was approached by a stranger in a van as he walked towards Ranui Station Rd.

The stranger asked him for directions before the child was pulled into the vehicle and taken to an unknown location, where he endured a four-hour ordeal. He was dropped off about 8pm.

The Education Ministry released an urgent alert to all Auckland schools, early childhood education centres and kura on Friday, after police released details of the incident.

Parents, caregivers and staff were urged to remain vigilant and to report any suspicious activity immediately to police.

Schools in the Ranui and wider West Auckland area - particularly in Henderson, Waitakere and Swanson - have sent out newsletters and warnings to parents, some on social media sites, encouraging them to speak to their children about stranger-danger.

anui Primary School, Summerland Primary School, Henderson Primary School and Henderson Intermediate School are among schools who have issued warnings to parents and students.

Ranui Primary posted a message to its local community via the school's Facebook page, saying: "As you may be aware, there was an incident involving an 11yr old West Auckland School student...in the Ranui area.''

The school asked parents to remind their children of key messages about being safe, including: "If a driver stops and asks you for directions, be polite but stay out of reach. If you don't know them or trust them, walk away quickly in the opposite direction.''

Students were told not to accept a lift from a stranger, to scream or yell for help if necessary and to go to the nearest place where there are other people - such as a dairy, a petrol station, school office or bus stop - if they felt unsafe.

Pupils were also encouraged to walk home with friends.

Police continue to appeal for any sightings of a grey van in the Ranui area between 3.55pm and 8pm on Thursday.

• Can you help? Anyone with information is urged to call Detective Senior Sergeant Jason McIntosh on: 021 191 2659 or CrimeStoppers anonymous on: 0800 555 111.