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(NBC NEWS) - Former CNN anchor Don Lemon was taken into custody by federal authorities on Thursday night, according to his attorney.

Lemon was taken into custody by federal agents last night in Los Angeles, where he was covering the Grammy awards, his attorney, Abbe Lowell, said in a statement.

"Don has been a journalist for 30 years, and his constitutionally protected work in Minneapolis was no different than what he has always done," Lowell said. "The First Amendment exists to protect journalists whose role it is to shine light on the truth and hold those in power accountable.

"There is no more important time for people like Don to be doing this work," Lowell added.

The Justice Department promised to pursue charges against Lemon after the independent journalist covered a protest in a church in St. Paul, Minnesota, last week.

His arrest comes after federal authorities arrested three protesters who attended the same demonstration.