Arizona Democratic Rep. Raul Grijalva, a vocal opponent of his state's controversial immigration law, has closed his district office in Yuma after a bullet was discovered inside, the Hill reports.
In a statement, Grijalva's office said one of the office windows had been shattered.
"A shattered window and bullet inside the office were found earlier today. Police are investigating the incident and have not released details about a potential motive," his office said. "Rep. Grijalva intends to open the office again as soon as possible."
The bullet was found one day after a judge blocked the most controversial parts of the Arizona immigration law, which went into effect today. Opponents of the measure held protests in Phoenix in conjunction with the law going into effect.
As the Associated Press notes, Grijalva called for a boycott of his state after the immigration law passed. He rescinded that call after the judge's decision.
Following passage of the health care bill in March, lawmakers faced threats and had bricks thrown through office windows, among other violence.