Residents in parts of Almere, Lelystad, Biddinghuizen and Emmeloord reported hearing a brief, low sound on Friday and Saturday evenings that resembled a ship’s horn. The sound was identified as a test tone from the air-raid warning system. According to the Flevoland fire service, the evening test tones and the later delay were separate events. The monthly warning-siren test on Monday did not begin at noon as scheduled, but was heard at around 12:07. The activation requires a dispatcher to start the system manually. Geert-Jan Veenstra of the Flevoland fire service said the dispatch room was very busy around noon, which caused the activation to be delayed by several minutes.