Federal authorities on Tuesday said the man accused of killing a Santa Cruz County Sheriffs official and an Oakland security guard had ties to the Boogaloo movement.

But what is it?

The movement started in alt-right culture on the internet with the belief that there is an impending civil war, said Devin Burghart, director of the Institute for Research and Education on Human Rights in Seattle. The two main aspects that differentiate Boogaloo Bois, as they call themselves, from other right-leaning militia-type groups are that they are younger and they are more likely to turn to acts of violence.

They are really violent, Burghart said. Armed conflict is at the core of their ideology.

Dr. Lawrence Rosenthal, director for the Center for Right-Wing Studies at UC Berkeley, said the movements origins are rooted in the history of the militia right in the United States, holding that patriots will rise up and lead to a second civil war.

While the movement overlaps with white nationalism, its supporters are centered more on the right to bear arms and not being subjected to constituted authority, Rosenthal said.

Another aspect that differentiates the movement from other extremist ones is its culture, like wearing distinctive patches and Hawaiian shirts.

The name itself is believed to come from the film Breakin 2: Electric Boogaloo, playing off the idea that the boogaloo is a sequel to the Civil War.

The FBI special agent who wrote the criminal complaint in the Santa Cruz and Oakland killings wrote that the movement was not a defined group but in general, followers of the Boogaloo ideology may identify as militia and share a narrative of inciting a violent uprising against perceived government tyranny.

Its difficult to estimate how many members or supporters the movement has, Burghart said, but there have been several recent real-life mobilizations, including three Nevada men who were recently arrested for allegedly plotting to terrorize protests in Las Vegas.

It has gained traction in recent months during the demonstrations to reopen the economy, he added.

Alejandro Serrano is a San Francisco Chronicle staff writer. Email: alejandro.serrano@sfchronicle.com Twitter: @serrano_alej

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What we know about the 'Boogaloo Bois,' the far-right group tied to killings in Santa Cruz and Oakland - San Francisco Chronicle