A U.S. Secret Service agent has been accused of groping and sexually harassing a member of Vice President Kamala Harris’ official staff during a trip last week, according to three people familiar with the matter.

The Secret Service Office of Professional Responsibility is investigating a misconduct allegation involving an employee, according to the agency, which is tasked with protecting the president, vice president, candidates, their families and some members of Congress. “The Secret Service holds its personnel to the highest standards,” according to the statement released Wednesday.

Harris’ office said in a statement that “we have zero tolerance for sexual misconduct,” and that the office takes “safety of staff seriously.”

The agent was on a trip with Harris staff members last week in Wisconsin to scout possible locations for a visit from the Democratic presidential nominee when the group went out for dinner and drinks. The agent, who appeared to be drunk, is accused of groping the woman in the presence of others after they went back to their hotel, according to the people who spoke to the Associated Press on condition of anonymity to talk about an ongoing investigation.

The employee was taken off his detail and placed on administrative leave pending the results of the investigation, the Secret Service said.

The news comes as the agency is facing a mountain of criticism over two attempted assassinations of Republican nominee Donald Trump. On July 13, Trump suffered a graze wound to his ear when a shooter targeted him at a rally in Butler, Pa. A second apparent assassination attempt was foiled on Sept. 16 at Trump’s golf club in West Palm Beach, Fla.

A scathing bipartisan congressional report out Wednesday on the first attempted assassination found that there was no clear chain of command among the Secret Service and other security agencies and no plan for coverage of the building where the shooter positioned himself on the roof to fire the shots in Butler. The shooter was killed within seconds by the Secret Service.

Miller, Long and Balsamo write for the Associated Press.