WASHINGTON (AA) Authorities have taken into custody a former U.S. Army infantryman who sought to bomb a rally in the state of California, investigators announced Monday. Mark Steven Domingo, 26, was arrested Friday when he went to a park in Long Beach to surveil the site of the rally planned for last weekend, the Justice Department said in a statement. The department said he previously asked someone whom he thought was a collaborator, but was in fact a confidential FBI informant, to find a bomb maker to construct an improvised explosive device. Domingo allegedly purchased several hundred nails last week, which were to be used as shrapnel in the bomb, and handed them over to the informant. “Domingo said he specifically bought three-inch nails because they would be long enough to penetrate the human body and puncture internal organs,” according to the affidavit. He took possession of several inert explosive devices, which he believed were weapons of mass destruction, from the FBI source last Friday and was arrested at the site of the rally later that evening.

“This investigation successfully disrupted a very real threat posed by a trained combat soldier who repeatedly stated he wanted to cause the maximum number of casualties,” U.S. Attorney Nick Hanna said in a statement.

Prior to selecting the Long Beach rally, Domingo mulled attacking Jews, churches and police officers, according to the Justice Department. He also allegedly contemplated using a modified AK-47-style assault rifle to carry out a drive-by shooting.

Domingo has been charged with attempting to provide and providing material support to terrorists and is scheduled to make an initial court appearance later Monday. He faces a statutory maximum sentence of 15 years in prison.

Following a deadly attack on two New Zealand mosques that killed 50 people, Domingo wrote on social media “there must be retribution,” and said in online posts that he wanted to be a martyr.