Updated: 8:06 p.m.

The FBI arrested four men Monday after they allegedly interfered with the telephones in Sen. Mary Landrieu’s (D-La.) New Orleans office by pretending to be repairmen.

Among those arrested, according to an FBI press release, was James O’Keefe, the conservative filmmaker who dressed up like a pimp and videotaped ACORN officials giving him incriminating advice on how to avoid getting caught. O’Keefe, 25, was joined by 24-year-olds Joseph Basel, Robert Flanagan and Stan Dai. Flanagan is the son of acting U.S. Attorney Bill Flanagan in Shreveport, La., according to the Associated Press.

Flanagan and Basel dressed in “blue denim pants, blue work shirts, light green fluorescent vests, tool belts, and construction-style hard hats— and requested access to the reception desk’s telephone, according to the complaint. Meanwhile, O’Keefe was “holding a cellular phone so as to record FLANAGAN and BASEL.—

“FLANAGAN and BASEL then manipulated the telephone system,— according to the press release, which doesn’t explain how they manipulated the phones. “FLANAGAN and BASEL next requested access to the telephone closet because they needed to perform work on the main telephone system.—

Both men said they had left their credentials in the car, and the U.S. Marshals Service arrested them soon after, according to the release. The complaint claims that O’Keefe and Dai helped in the “planning, coordination, and preparation of the operation.—

Landrieu issued a statement saying the situation was “unusual— and “somewhat unsettling— for her and her staff.

“The individuals responsible have been charged with entering federal property under false pretenses for the purposes of committing a felony,— Landrieu said in the statement. “I am as interested as everyone else about their motives and purpose, which I hope will become clear as the investigation moves forward.—

O’Keefe is best known for his undercover videos at Association of Community Organizations for Reform Now field offices, where officials seem to give O’Keefe and a young woman — disguised as a pimp and a prostitute — advice on how to avoid taxes for an underage prostitution ring.