Complex sentence: With the traps deactivated, Katniss and Gale infiltrate the refugees to gain access to Snow, but are exposed and nearly captured before the Rebels arrive and attack the Peacekeepers.
Split into simpler sentences: With the traps deactivated, Katniss and Gale infiltrate the refugees to gain access to Snow. Their cover are nearly blown before the Rebels arrive and attack the Peacekeepers.