Investigators believe the man may have been livestreaming the shooting and were looking into whether he had posted a manifesto online, the official said.The supermarket is in a predominately Black neighborhoodWitnesses reported the gunman was wearing military-style clothing in addition to the body armor, one of the officials saidThey described him as a white male in his late teens or early twenties sporting full camo, a black helmet and what appeared to be a rifle.