What happened in final minutes before Boeing 737 cargo plane vanished off Pakistan coast?

A Boeing 737 cargo plane operated by Pakistan's K2 Airways vanished off the coast of Karachi on Tuesday. Flightradar24 data showed the plane plunged nearly 5,000 feet in under a minute before climbing about 6,000 feet in just 30 seconds. It then dove from 36,550 feet, and the last transmitted data placed the aircraft at 1,100 feet above sea level.