A 13-year-old schoolgirl has been arrested on suspicion of possessing drugs with intent to supply after a number of pupils fell ill.

Police were called to St Mark’s West Essex Catholic school in Harlow after reports that eight girls had taken a class B drug. Two were treated by paramedics; a third was taken to hospital.

All pupils affected by the “unprecedented incident” had been discharged from hospital, the school confirmed.

It said: “On Thursday 28 February, a pupil brought a substance into school. Subsequently, a small number of pupils felt unwell and notified school staff … This unprecedented incident was dealt with quickly and efficiently, in accordance with health and safety procedures; the safety of pupils was paramount at all times.

“A full investigation into the incident will now take place.”

The teenager was released under investigation.