A banging sound is believed to have triggered a shootout at an Alabama Sweet 16 party, where 89 bullets were fired from at least seven guns. The April 15 chaos began after a stereo speaker fell with a loud thud, Special Agent Jess Thornton reportedly said at a Tuesday morning bail hearing. That fallen speaker seemingly prompted several partygoers to lift their shirts to show they were packing heat inside the 38-foot-by-20-foot Mahogany Masterpiece dance studio, where up to 60 people showed up to celebrate Alexis Dowdell’s birthday. When Dowdell’s mom said any minors carrying guns had to leave,...