Following a weekend of false alarms, three local communities will test their sirens Thursday afternoon.

Cedar Hill, DeSoto and Duncanville will test outdoor warning sirens at 2 p.m. Officials stress there is no need to be alarmed. It is only a test.

The city of Dallas confirmed Monday that a lack of encryption of the signal transmitted to 156 sirens led to the hack that kept Dallas residents awake late Friday and early Saturday.