Students hospitalised on Central Coast after ingesting 'unknown substance'

Four students at a Central Coast high school were hospitalised on Friday after ingesting an "unknown substance".

A NSW Ambulance spokeswoman said paramedics were called to Brisbane Water Secondary College at Umina about 11am and assessed 15 students who had "fallen ill".

Four of those students were taken to Gosford Hospital as a precaution and to undergo observation.

Police said initial inquiries established a group of students had ingested an unknown substance before feeling unwell.

"The students were assessed by NSW Ambulance paramedics before being taken to Gosford Hospital for observation," police said in a statement.

"The substance has not been located or identified."

The school was not evacuated as a result of the incident.

Brisbane Water police attended the school and were on Friday making inquiries about the source of the substance.

A NSW Department of Education spokesperson said the school was looking into a "concerning incident".

"Our student's safety and wellbeing are our highest priorities," the spokesperson said.

"Four students were transported to hospital by ambulance.

"They are in a stable condition.

"Three other students were assessed by paramedics at the school and released into the care of their parents."