BOSTON (AP) — The daughter of U.S. Rep. Katherine Clark of Massachusetts was arrested during a protest Saturday night on Boston Common and later charged with assault after a police officer was injured.

In a statement on its website, the Boston Police Department said the 23-year-old was expected to be arraigned in Boston Municipal Court.

Clark, the House Democratic whip, said in a tweet that her daughter, Riley Dowell, had been arrested. “I love Riley, and this is a very difficult time in the cycle of joy and pain in parenting,” Clark wrote. “This will be evaluated by the legal system, and I am confident in that process.”

Clark has spoken publicly about the fears of her own nonbinary child amid bigotry targeting transgender people.

Police said officers responded to a report at the Parkman Bandstand Monument located within the Boston Common. They found a person, identified as Dowell, a resident of Melrose, defacing the monument with spray paint and anti-police phrases, according to police.

During the arrest, “a group of about 20 protesters began to surround officers while screaming profanities though megaphones on the public street causing traffic to come to a standstill,” police said, adding that “an officer was hit in the face and could be seen bleeding from the nose and mouth.”

Dowell was charged with assault by means of a dangerous weapon, destruction or injury of personal property, and damage of property by graffiti/tagging, police said.

A fatal police shooting earlier this month in nearby Cambridge sparked protests over use of force. A 20-year-old student at the University of Massachusetts Boston, Sayed Faisal, was shot and killed by Cambridge police. He had advanced on officers with what police described as a kukri, a type of sword, and a less-than-lethal “sponge round” had failed to stop him, police said.

Clark is in her sixth term in the House and represents the state’s 5th Congressional District.