Four members of a California militia group associated with the anti-government “boogaloo” movement were indicted Friday on charges of conspiracy to obstruct justice in connection with a scheme to destroy records related to last year’s killing in Oakland of a federal Protective Services officer and the wounding of his partner, the U.S. Justice Department said.

The men are accused of conspiring to destroy communications and other records about the May 29, 2020, killing of federal security officer David Patrick Underwood and attempted murder of his partner as they guarded the Ronald V. Dellums Federal Building in Oakland.

The officers were shot while a large demonstration over the police killing of George Floyd in Minneapolis was underway nearby. Prosecutors said Air Force Staff Sgt. Steven Carrillo, 32, fatally shot Underwood and wounded his partner. They said Carrillo used the protest as cover for the crime and for his escape. Carrillo has pleaded not guilty.

Days later, Carrillo, who had ties to the “boogaloo” movement, ambushed and killed a California sheriff’s deputy and injured four other officers in Santa Cruz County, authorities said. Carrillo is awaiting trial on murder and attempted murder charges. He has pleaded not guilty.

The men indicted Friday are Jessie Alexander Rush, 29, of Turlock, California; Robert Jesus Blancas, 33, a transient resident of the Bay Area; Simon Sage Ybarra, 23, of Los Gatos, California; and Kenny Matthew Miksch, 21, of San Lorenzo, California.

The indictment alleges that Rush, Blancas, Ybarra and Miksch, along with Carrillo, were members of the Grizzly Scouts, a militia group based in Northern California that connected via a Facebook group and periodically met in person for firearms training, federal prosecutors said.

Boogaloo adherents are part of a loose, anti-government, pro-gun extremist movement. The name is a reference to a slang term for a sequel — in this case, a second U.S. civil war.

According to the indictment, members of the Grizzly Scouts, including Rush, Blancas, Ybarra, Miksch, Carrillo and others, communicated with each other on June 1, 2020, and June 2, 2020, using a WhatsApp group in which discussions repeatedly referenced “boog” and tactics involving the killing of police officers and other law enforcement.

Carrillo exchanged messages on the WhatsApp group with other Grizzly Scouts and told the group on June 6, 2020, that he was preparing to engage in a shoot-out with law enforcement, authorities said. He asked the other Grizzly Scouts to come to his aid, according to court documents.

The indictment alleges Rush immediately instructed Carrillo on the WhatsApp group to “factory reset” his phone, and that Blancas deleted files related to the Grizzly Scouts from a Dropbox account less than an hour after the June 6, 2020, shootings in Santa Cruz County.

It also alleges the four defendants each deleted records of the WhatsApp group communications from their phones. The indictment says one message from Carrillo read, “Dudes i offed a fed.”

Rush, Blancas, Ybarra and Miksch are charged with conspiracy to obstruct justice by destroying records, and the destruction of records in official proceedings. Rush is charged with an additional count of obstruction of official proceedings and Blancas is charged with an additional count of destruction of records in official proceedings.

Ybarra was scheduled to appear in federal court Friday for a detention hearing. The other three men are in federal custody. It wasn’t immediately known if they have attorneys who could speak on their behalf.

If convicted, they each could face a maximum statutory penalty of up to 20 years in prison and a fine of $250,000 for each of the conspiracy, obstruction and destruction charges.