BETHLEHEM, Pa. (AP) — A man officials say was part of an unrealized plan to set off a bomb at a recent music festival has been charged with involvement in the detonation of at least four other explosive devices around the northeastern Pennsylvania city of Bethlehem, authorities said Tuesday.

Federal and local law enforcement agents searched the Bethlehem home of Robert L. Bowen Jr., 53, on Aug. 4 and found bomb-making materials, two modified grenades, drugs including methamphetamine and heroin, and a homemade “zip gun,” authorities said. He was charged with possession of weapons of mass destruction and related counts.

Investigators got a tip that took them to Bowen’s home, where they found and confiscated the items, Northampton County District Attorney Terence Houck said.

Prosecutors said they did not know whether Bowen has an attorney to comment on his behalf, and online case files that could indicate such did not appear to be available Tuesday. He remained in jail Tuesday with bail set at $500,000.

The raid came a day after authorities learned Bowen was “actively involved” in a plan to detonate a bomb at Musikfest, an annual music festival in the Bethlehem area, according to court documents. The event concluded Sunday without incident.

“What ultimately his intentions were, because they got him so soon, we’re lucky not to know for sure,” Houck said.

Confidential informants told authorities in early July that Bowen had detonated a bomb under a bridge in the Bethlehem area, and a second explosion was reported there later in the month. Two other explosions occurred at undisclosed sites in the city of 77,000 people about 50 miles northwest of Philadelphia. No injuries were reported in any of the explosions.

A fifth explosion that occurred in Bowen’s neighborhood was captured on a resident’s doorbell camera. The video showed someone on a motorcycle put something underneath a vehicle before an explosion occurred. The date of the explosion was not released.