METHUEN (CBS) — A private Catholic stepping up security and delayed its opening Thursday morning after threatening writings were found on the walls.

The Presentation of Mary Academy delayed classes until 8:25 Thursday morning. Students had to go through metal detectors and have their bags searched as they entered the building.

“We take threats serious, so if you’re a young kid and you think this is funny, we don’t think it’s funny,” Methuen Police Chief Joseph Solomon told WBZ-TV’s Anna Meiler.

Presentation of Mary Academy in Methuen. (WBZ-TV)

Officers were present at the school Thursday morning, along with a school threat assessment team, to perform what they call a controlled entry.

It’s not clear exactly what was written on the wall, or where the writings were found–but Solomon said the threat was found outside the school, not inside.

“There’s three different threats that were determined,” Chief Solomon said. “They were extremely concerning.”

Police have not detailed the threat, but said they are investigating and taking precautions.

“Safety first. That’s very important in today’s day and age and we all know what’s going on in our country. So I want the parents to feel at ease,” said Mayor Stephen Zanni.

Chief Solomon said two of the threats were more serious, and classified the third as lower-level.

“To the parents and the students we’re going to do everything in our power to make sure you’re safe,” Solomon said. “If we thought you shouldn’t come to school we would have told you and we have canceled school before.”

The chief expressed thanks to the student who saw the message and reported it and had a message to whoever wrote the threats.

“We take it seriously. We will charge you,” Solomon said.

Several parents told WBZ-TV they were grateful for the increased security.

“It’s uneasy that this has to happen and that’s the world we live in. It’s just sad,” one parent said.