A teenager arrested in relation to “prank” death threats against teachers at his school will be considered for inclusion in the Juvenile Diversion Programme.

Gardaí in north Dublin arrested a 16-year-old boy on Monday night, shortly after repeated comments were posted online threatening to “shoot up” Ardgillan Community College in Balbriggan the next day.

Detectives questioned the youth and Garda sources said they were satisfied threats against two teachers were a “prank gone wrong”.

Management at the school alerted parents at around 7.50am yesterday to say the school would be closed for the day.

A post on the youth’s social media account on Monday night said: “I think I’m a shoot up Ardgillan Community College tomorrow.”

Another post said: “Don’t come in tomorrow if you have any regard for your life, you’ve been warned. “Think I’m joking, you’ll see tomorrow.

When gardaí were alerted they responded immediately.

“It was taken very seriously as this was death threats against teachers, two teachers,” said a source.

The teen was detained under Section 4 of the Criminal Justice Act and questioned overnight.

Detectives are happy this was a prank,” said a garda source. “It was a prank gone wrong, a terrible prank.

The Garda Press Office said: “Gardaí are liaising with management at the school and are now satisfied that there is no imminent danger to staff or students attending the school.”

The boy was released from custody yesterday morning.

He had not come to the attention of gardaí before.

Sources said investigators will refer the case to the Garda National Juvenile Office. It will examine if it should be included in the Juvenile Diversion Programme, which takes minors out of the criminal justice system. It will assess the seriousness of the offence and whether the youth admits involvement. The office can refer cases to the DPP if the offender is deemed unsuitable.

Sources said community gardaí will visit the school “to talk to pupils about online safety and responsible use of the internet”.

A school spokesman said it was reopening this morning after gardaí advised there was “no cause for further concern”. He confirmed a pupil had been suspended.