On Tuesday, an explosive device detonated near a polling station in Catasauqua, Pennsylvania, during the state’s Democratic primary for the 7th Congressional District.

Pennsylvania State Police responded to the Salem United Church of Christ—a polling site located in the area—after reports of an explosion at the intersection of Walnut and 3rd streets. First responders recovered remnants of an “M-type” explosive device consistent with homemade constructions.

Authorities arrested Matthew Pletz, 57, and Jack Pletz, 25, on Wednesday, charging them with weapons of mass destruction after discovering 17 illegal explosives in their possession. According to a criminal complaint, the suspects were allegedly inside a green 1998 Chevrolet pickup truck when the device detonated. Security footage shows Matthew and Jack Pletz at the scene moments before the explosion, fleeing into a plume of smoke.

Local election officials confirmed that road closures following the incident have drastically reduced voter turnout despite polls remaining open. Catasauqua Judge of Election Louis Draxler stated voters were arriving steadily prior to the event but have since been unable to reach the site due to blocked streets.