MANCHESTER, N.H.- At least a dozen schools received bomb threats Tuesday and Wednesday this week that police determined were not credible.

Police departments increased their presence at schools Wednesday out of an abundance of caution in Londonderry, Nashua, Pelham and Litchfield.

State police released a statement saying they were working with local law enforcement agencies and that these reports are believed to be a hoax, however, all threats will be taken seriously.