MILWAUKEE — A 20-year-old man from California has been taken into custody for allegedly planning a mass shooting at a governmental facility in relation with the Madison school shooter, as per court documents.

FBI agents have arrested Alexander Paffendorf, from Carlsbad, California, following an emergency gun violence restraining order examined by the Milwaukee Journal Sentinel, part of YSL News Network. In Wisconsin, authorities reported that Natalie “Samantha” Rupnow, a 15-year-old, fatally shot a student and a teacher and wounded six others at Abundant Life Christian School earlier this week.

This arrest was first reported by CBS 8 on Wednesday.

“During an interview with the FBI, Paffendorf acknowledged that he informed Rupnow of his intention to acquire explosives and firearms to attack a government building,” the restraining order states.

The order specifies that FBI agents were shown the communication between Paffendorf and Rupnow.

In an interview with the Journal Sentinel on Wednesday night, Madison’s Police Chief Shon Barnes stated he lacked details concerning the California detention and redirected inquiries to the FBI. However, a representative from the FBI’s San Diego office declined to provide any comments. YSL News also sought clarification from the Carlsbad Police Department on Wednesday.

A San Diego judge sanctioned the restraining order on Tuesday, mandating Paffendorf to hand over any firearms and ammunition he possessed and forbidding him from acquiring any in the future.

Shortly after the judge’s order, local residents in Carlsbad noticed a substantial police presence, with over a dozen police vehicles arriving at the apartment complex. Neighbor Alex Gallegos recounted to CBS 8, “They had their guns drawn all over the street. I’d estimate about 15 police officers were present.”

Paffendorf has a court hearing scheduled for January 3.

Authorities disclosed that Rupnow, a freshman at Abundant Life Christian School, brought two handguns to school on a Monday, but only one was reportedly used during the incident.

This article was updated to include additional information.