Complex sentence: First shots were fired at a German patrol at 13:35 PM on Krasinski Street in Żoliborz by members of Zdzisław Sierpinski's team, who were transporting weapons for a unit of the "Reaper" Group.
Split into simpler sentences: First shots were fired at a German patrol at 13:35 PM on Krasinski Street in Żoliborz by members of Zdzislaw Sierpinskis team. They were transporting weapons for a unit of the "Reaper" Group.