A TEEN who threatened to stab a teacher at a Brentwood school has ignited a police enquiry.

The incident happened at St Martin’s School, in Hanging Hill Lane on Thursday at about 2.30pm.

A boy, believed to be 14, who was outside the school’s periphery, was talking to pupils through a fence.

When a male teacher stepped in to disburse the gathering, the boy threatened to “stab him up”, according to head teacher Mike O’Sullivan.

He explained: “The teacher didn’t see a knife, but you cannot be certain in these kind of incidents.

“The member of staff who was on duty moved the pupils on, and when he asked the boy to leave the boy said he was going to stab him up.

“The member of staff wasn’t shaken, he laughed it off.

“I want to make it clear that this an unprecedented incident in my six years at the school.”

Mr O’Sullivan added parents should not be worried, and praised the behaviour of the majority of the school's pupils.

Staff will thrash out introduced new lock-down arrangements, following the incident.

Mr O’Sullivan continued: “We are an open school and do not have a fence running around the entire periphery.

“Unfortunately the cost of building one is just too expensive.

“We are going to strengthen up our lock down arrangements but the site is very large.”

Enquiries are ongoing, according to an Essex Police spokesman.

He added: “Police were called to St Martin’s School in Hanging Hill Lane, Hutton, at about 2.30pm on June 23 with reports a teenage boy had made threats.

Meanwhile, pupils at the school will continue to be educated on the dangers of carrying knives.

Mr O’Sullivan explained the school holds “down days”, where pupils are taken out of class to be educated on the dangers of carrying weaponry.

He said: “We take children out of class and teach them about knife crime.

“We teach children that if you have a knife, even if you don’t intend on using it, it’s more likely you will be a victim of knife crime.”