Complex sentence: The Police began questioning the Unit 124 members and when a Police officer grew suspicious and drew his pistol he was shot by a Unit 124 member, a running gun battle then developed in which 2 members of Unit 124 were killed.
Split into simpler sentences: The Police began questioning the Unit 124 members and when a Police officer grew suspicious and drew his pistol he was shot by a Unit 124 member. A running gun battle then developed in which 2 members of Unit 124 were killed.