The FBI arrested multiple police officers in the California cities of Antioch and Pittsburg early Thursday in a series of raids conducted as part of an ongoing investigation into their embattled police departments. The raids were executed in multiple locations across the Bay Area after a federal grand jury in San Francisco handed down an indictment, according to the Bay Area News Group, which first reported the development. The arrested officers have been accused of a “wide range of offenses, including criminal conspiracy,” according to the outlet. Both the FBI and Contra Costa County District Attorney’s Office have been probing the cities’ law enforcement agencies since last year. After seizing several cell phones from Antioch officers, investigators discovered thousands of racist and homophobic text messages swapped between members of the department. As many as 45 of Antioch’s 100 police officers were subsequently placed on leave, with the state attorney general’s office opening its own investigation in May. On Thursday, Antioch Mayor Lamar Thorpe said in a statement, “Today is a dark day in our city’s history... As our city absorbs this tragic news, we must come together as one.” The indictment is expected to be unsealed later on Thursday.