Warning: the following story includes disturbing content.
Authorities now know what happened on the Eisenhower Expressway last Thursday, leading to a bomb squad response and shutting down the interstate for hours.
It was a firework mortar that went off inside the SUV being driven by 47-year-old Jorge Vaca from west suburban Cicero. A senior law enforcement official with direct knowledge of the case told NBC Chicago the fireworks rocket was ignited inside Vaca’s vehicle and shot into his chest…