I don't know if you heard it but the legend says:
"During one of the Mongol invasion of Poland (usually the invasion of 1241), Mongol warriors, led by General Subutai, approached the city. A guard on the Mariacki church tower sounded the alarm by playing the Heynal, and the city gates were closed before the Tatars could take the city by surprise. The bugler, however, was shot in the throat and did not complete the tune. According to the legend, that is why it now ends abruptly before completion".