The FBI and Texas Department of Public Safety have raided Laredo municipal offices, the Webb County Courthouse and other offices as they seized materials and sent employees home.
County officials said in a statement Wednesday that the auditor's office, information technology and other offices will remain closed until further notice.
City spokeswoman Blasita Lopez told the Laredo Morning Times that agents directed city hall employees to step away from their work stations.
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In a statement, the FBI declined to reveal what prompted the raid but said there's no threat to public safety.
Agents also raided a private engineering company in Laredo and Houston. In a statement, an attorney for Dannenbaum Engineering said the firm is cooperating with federal agents and is performing its own investigation into what prompted the raid.