Complex sentence: One team engaged a group of USMC mechanics from VMM-161 who were in the area, the same team had attacked the aircraft refueling stations, one group attacked the aircraft, the last group was engaged at the base cryogenics compound.
Split into simpler sentences: One team engaged a group of USMC mechanics from VMM-161 who were in the area; the same team had attacked the aircraft refueling stations. Another group attacked the aircraft, and the last group was engaged at the base cryogenics compound.