Bullet holes were found in the front windows of a Democratic Party campaign office in Arizona on Monday, police said.

Police in Tempe, just east of Phoenix, are investigating the gunfire damage, NBC News reports. The shooting took place just days before Vice President Kamala Harris is scheduled to visit the swing state as part of her presidential election campaign.

The office, which is used by the Harris presidential campaign and state Democratic congressional candidates, was also shot at a week ago by someone using a pellet or BB gun, according to police.

“We are grateful to Tempe Police for coming quickly to the scene and are fortunate no one was present or injured,” said Sean McEnerney, the Arizona Democratic Party coordinated campaign manager.

The incident is being treated as a property crime, as nobody was in the office when the bullets were fired.

“No one was inside the office during the overnight hours, but this raises concerns about the safety of those who work in that building, as well as those nearby,” said Sgt. Ryan Cook of the Tempe Police Department.

Recent years have been marked by a number of high-profile incidents and threats of political violence in the U.S., including the Jan. 6, 2021, Capitol insurrection, the attempted kidnapping of Michigan Gov. Gretchen Whitmer (D), and the bomb threat at the city hall building in Springfield, Ohio, amid heated anti-immigrant rhetoric from GOP nominee Donald Trump and his running mate, Sen. JD Vance (R-Ohio).

Trump himself has faced two suspected assassination attempts this year.