Students at Mamaroneck High School were greeted Friday with a strong police presence after a week of threatening messages disrupted classes.

School officials say threats on school walls have forced a series of evacuations this week for the middle and high schools. No explosive devices were ever found, but the ongoing situation is putting staff and students on edge. In an effort to put a halt to the disruptions, security was beefed up on campus and in the school.

Mamaroneck School Superintendent Paul Fried says every threat must be taken seriously. Fried says the school has banned backpacks and other bags are being searched as students enter the building. The superintendent hopes the new security measure will prevent any further threats. Police and school officials are working together to find whoever is responsible for the threats.