In an eight-day span, an Air Force sergeant fatally shot a federal security officer and wounded his partner outside a U.S. courthouse and ambushed and killed a California sheriff’s deputy and injured four other officers, federal authorities said Tuesday.

In announcing murder and attempted murder charges in the shooting of the security personnel, authorities alleged Staff Sgt. Steven Carrillo, 32, had ties to the far-right, anti-government “boogaloo” movement and that the plot to target them was hatched a day earlier during an online chat with an accomplice and a third person.

David Patrick Underwood, 53, was killed and his partner was wounded as they guarded the Ronald V. Dellums Federal Building in Oakland while a large demonstration over the police killing of George Floyd in Minneapolis was underway nearby. Officials said Carrillo used the protest as cover for the crime and for his escape.

“Pat Underwood was murdered because he wore a uniform,” David Anderson, U.S. attorney for the Northern District of California, said at a news conference at the Dellums building.

Department of Homeland Security Acting Secretary Chad Wolf called the killing an assassination.

Carrillo’s attorney, Jeffrey Strotter, said he doesn’t have any evidence his client was in contact with anyone in the boogaloo movement, which the lawyer called a terrorist organization that uses social media to reach out “to vulnerable and possibly susceptible individuals who may be receptive to their messages of hate and destruction.”

Carrillo “has personally expressed to me his sadness and sympathy for everyone that has been harmed by the tragic events in his case,” Stotter said.

Carrillo separately faces state charges in the June 6 fatal shooting of Santa Cruz County sheriff’s Sgt. Damon Gutzwiller and the wounding of four other officers in the community of Ben Lomond outside the beachfront city of Santa Cruz south of San Francisco.

Federal authorities say the same homemade AR-15-style rifle was used in the two shootings.

Carrillo was stationed at Travis Air Force Base northeast of Oakland where he was a leader in an elite military security force and had no record of disciplinary issues. Federal authorities say they linked him to the boogaloo movement from social media posts and from phrases he had written in his own blood when he was arrested following the ambush of the deputy.

The boogaloo movement got its name from the panned 1984 movie “Breakin’ 2: Electric Boogaloo” and uses the title as a code word for a second civil war, authorities say. Adherents have attended protests against government shutdowns over the coronavirus. They are easy to spot with their trademark Hawaiian shirts and high-powered rifles and tactical gear.

Facebook earlier this month moved to limit the movement’s exposure on its platform by no longer recommending user groups associated with the term “boogaloo” to members of similar associations. Other derivations of “boogaloo” are “big igloo” or “big luau.”

Federal authorities said they found an American flag-like patch on Carrillo’s bulletproof vest that depicted an igloo and a Hawaiian-style print.

Authorities do not believe the Oakland attackers coordinated with three Nevada men suspected of plotting to spark violence during recent protests in Las Vegas and identifying with the “boogaloo” movement.

In their criminal complaint, federal officials described a hastily hatched plan to target federal law enforcement officials during the protest in Oakland.

In a Facebook group that included his alleged accomplice, Robert Alvin Justus Jr., 30, and an unidentified third person, Carrillo linked to a video showing a crowd attacking two California Highway Patrol vehicles and wrote, “It’s on our coast now, this needs to be nationwide. It’s a great opportunity to target the specialty soup bois. Keep that energy going,” the complaint states

“Boogaloo” adherents refer to federal law enforcement as “soup bois” because federal agencies sometimes are referred to as “alphabet soup” due to their varied acronyms.

The complaint says Justus responded with “lets boogie.” The third member of the chat later wrote that Oakland might be “popping off” with police protests.

The next day, Carrillo drove from Travis Air Force Base and picked up Justus. He offered him body armor and a firearm. Justus, who turned himself in after the deputy was killed, told investigators he wouldn’t take the weapon and gear.

Justus said he drove Carrillo’s white van, parked it near the courthouse and then did a 10-minute walk around the area. Justus told investigators that he did not want to participate in the killing but felt he was forced to because he was trapped in the van with Carrillo.

According to the complaint, authorities reminded him that he had gotten out of the van and could have left at any time. Justus claimed he was trying to think of ways to talk Carrillo out of his plan.

After he returned to the van Justus drove past the guard station where Underwood and his partner were located and Carrillo fired from an open sliding door. Justus told investigators Carrillo seemed “thrilled” after the shooting, the complaint said.

Surveillance video showed the shooting and authorities asked for the public’s help finding the van. On June 6, a citizen spotted an abandoned white van in Santa Cruz County and reported noticing ammunition, firearms and bomb-making ingredients inside.

The vehicle identification number was traced to Carrillo’s home in Ben Lomond and that’s where authorities say he ambushed the officers, showering them with gunfire and explosives from a hillside.

Carrillo is being held without bail in jail in Monterey County. He is expected to enter a plea to the state charges next month. Justus is charged with aiding and abetting the murder and attempted murder of the federal officers.