Joshua Barnwell was shopping with a friend at the Allen Premium Outlets Mall in the Dallas suburb of Allen, Texas, when he said he heard "two pops" go off. Shortly after, "massive rapid gunfire" rang out, and he knew there was a shooter. He said he quickly took cover behind a concrete pillar with his friend and called 911. He also sent an SOS message to his emergency contacts, informing them of the situation. The shooter was heavily armed with an AR-style rifle and wearing body armor, according to law enforcement sources. Police said he fired dozens of rounds at...