D.C. police are investigating after a 15-year-old girl said she was injured during a confrontation with officers who stopped her and her younger brother as they sold plantain chips Tuesday evening on the street in Columbia Heights.

An advocacy group helping the girl, her 10-year-old brother and their mother, said police mishandled the incident and frightened the children, who were alone when the officer approached.

“It escalated in a way that it should never have,” said Megan Macaraeg, the labor organizer for Many Languages One Voice, an immigrant rights advocacy group. The mother is from Central America.

D.C. police spokesman Dustin Sternbeck confirmed that the teenager filed a complaint alleging unnecessary use of force. He declined to comment on the family’s account, citing the internal investigation.

The incident came amid concerns about unlicensed street vendors. The city says the carts do not follow health guidelines and other rules.

D.C. Council member Brianne K. Nadeau (D-Ward 1), who spoke with a police commander that night, said in a statement that she was concerned. She said she has been working to help unlicensed immigrant vendors in Columbia Heights, and “to foster understanding between them and our police.”

Nadeau called what happened Tuesday “a setback on that progress.”

The girl, Genesis Lemus, spoke at a news conference held by the advocacy group and attended by her mother. The eighth-grader said she often sells food on 14th Street and is sometimes alone. She said her brother sometimes accompanies her and plays with a friend and does homework inside a restaurant.

Genesis said the same officer who confronted her Tuesday had told her to pack up her food the day before. She said the officer approached her Tuesday and told her she couldn’t be there because she was a minor, and asked her where her mother was. She said he told her that if she didn’t provide identifying details, he would call child protective services.

Genesis said she explained that she and her brother did not need help. Other officers arrived, and Genesis said her brother overhead one tell another to get the boy. When he heard that, he ran, Genesis said, and an officer grabbed him. She said she intervened and injured her knee during a struggle, part of which was captured on video.

“This situation, it terrified me,” Genesis said. “All I ask is for them to leave us alone, for them to stop treating us like criminals. We are not criminals. We do not go and steal and be in gangs. We go out and sell tacos, chips, mangoes to make a living for ourselves. I do that to help my mother out.”

Genesis said the officer “should really feel ashamed of himself for what he did yesterday to me.” She said the officer was “threatening me that he was going to separate me from my family, that he was going to separate me from my little brother.”