California man Alexander Paffendorf accused of plotting co-ordinated attack with Wisconsin school shooter

A California man has been arrested for allegedly plotting a coordinated attack with Wisconsin school shooter Natalie 'Samantha' Rupnow.

Alexander Paffendorf, 20, of Carlsbad, was detained by FBI agents on suspicion of 'plotting' to coordinate a mass shooting at government buildings in conjunction with Rupnow, according to an emergency gun violence restraining order reviewed by the Milwaukee Journal Sentinel. 

'During an FBI interview, Paffendorf admitted to the FBI agents that he told Rupnow that he would arm himself with explosives and a gun that he would target a government building,' the order says. 

It notes that FBI agents 'saw the messages from Paffendorf to Rupnow.'

A San Diego judge approved the order on Tuesday, and required Paffendorf to surrender any firearms and ammunition, and prohibited him from acquiring any more.

Shortly afterwards, neighbors told CBS 8 they saw more than a dozen police cars enter the apartment complex where Paffendorf lives.

'They had their full guns out all over the street,' neighbor Alex Gallegos said. 'They were cop cars. I'd say about 15 cops here.' 

He said he saw police coming out of the building carrying what he described as a 'black gun box.'

'I saw them carrying out the big box. I didn't see them arrest anybody, but they gave high-fives as it came to an end.'

It was not immediately clear how Paffendorf knew Rupnow, and Madison Police Chief Shon Barnes told the Journal Sentinel he did not have any information about the arrest in California, and referred questions to the FBI.

This is a breaking news story and will be updated.