Bayonne students returned to school Tuesday to find an increased police presence after a series of online threats made against the school.

The latest threat came early Tuesday morning when a Twitter user posted “You think you guys evacuated the school but that was all part of the plan. @BayonneBOE watch your back I’ll be coming.”

The tweet was in response to the fact that all Bayonne schools were closed Monday after authorities were alerted to another tweet over the weekend that threatened to shoot up Bayonne schools Monday morning.

“Unfortunately it doesn’t sound like a joke anymore. I am very upset,” said one parent outside Bayonne High School.

Schools were open Tuesday, but many parents wrote on Twitter that they were going to keep their children home until the person making the threats was found.

“Today you will have police officers in front of all the schools, you will have roving patrol cars, and there will also be police officers in every single school, inside the schools,” said Bayonne Mayor Jimmy Davis.

Davis added that Bayonne will not be held hostage by those making threats online. The FBI and Bayonne Police Department are working to track down the person responsible. Making online threats is a felony in New Jersey and can carry a sentence of up to five years in prison.

Dozens of schools in New Jersey have had to be evacuated or put into lockdown nearly every day due to threats made online or found written in the school since the Feb. 14 mass shooting of a high school in Florida.