In a battle between Nitro and the New Warriors, Nitro exploded, seemingly killing the entire team and a huge number of civilians (including 60 school children nearby). This led the United States government to introduce a "Living Weapon of Mass Destruction" registry for all super-powered individuals. Most heroes were divided on the issue, and a Civil War ensued.The Superhuman Registration Act had been a long time in the making. The logical extension of the often-proposed, never-passed Mutant Registration Act, the Superhuman Registration Act arose following the devastating attack on Manhattan in reprisal for Nick Fury's "Secret War" and the Hulk's destructive rampage in Las Vegas, which killed 26 adults, 2 children, and a dog (unbeknownst to the general public, the Illuminati subsequently deceived the Hulk and jettisoned him into space following this incident
