An explosion in New Jersey on Sept. 17 marked the start of a busy two days for grassroots jihadists in the United States — and for the law enforcement officers responding to the attacks. The 48 hours that ensued went as follows: Saturday, Sept. 17 09:35 EST — Seaside, New Jersey: A bomb exploded in a plastic trashcan along the route of a planned 5K race for charity. Only one of the three pipe bombs bundled together detonated, and nobody was injured in the blast. 20:30 EST — New York: A pressure-cooker bomb exploded at a construction site in Manhattan's Chelsea neighborhood, injuring 29 people. 21:15 EST — St. Cloud, Minnesota: Dahir Adan stabbed 10 people at a mall before an off-duty police officer shot and killed him.