Complex sentence: The bouncing balls that started shooting from his body scared onlookers and he was being put into custody by San Diego Police officers when they were interrupted by Cyclops and his group of X-Men who showed up at the scene to rescue him.
Split into simpler sentences: The bouncing balls that started shooting from his body had scared onlookers and he was being put into custody by San Diego Police officers. However they were interrupted by Cyclops and his group of X-Men who arrived to rescue him.