ST. LOUIS — Dawn Usanga said a majority of the photos and videos of her 7-year-old son Xavier are saved on her cellphone. Xavier was hit and killed by a stray bullet while walking in his neighborhood in August. He was one of more than a dozen children killed in St. Louis over the summer.

RELATED: 13 children were killed in St. Louis this summer and only one case has been closed

RELATED: Xavier Usanga, 7

Usanga said her phone was stolen after she was assaulted on a MetroLink train on Saturday evening.

"I took four punches to the face," Usanga said. "He broke my nose."

Usanga said it all started when a group of teens on the train got into a fight.

"Some Metro officers got on and broke it up," Usanga said. "They talked to them, and then the officers got off the train."

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Usanga said the teens stayed on the train.

"He was threatening people," Usanga. "It was getting out of hand. Some people were recording him. He didn't like that, and he started threatening to take one of the passenger's phone that was recording him."

Usanga said she spoke to the teens twice.

"I told them to stop," Usanga said. "This behavior is absolutely unacceptable. You need to stop what you're doing."

Usanga said she grabbed a teen by his hoodie and told him to stop, and he punched her in the face four times. 

She said she got to the next stop, Grand, and got off without her cellphone. She said officers rushed to her to help stop the bleeding. She was left with two black eyes and a broken nose. 

Usanga said she spoke to a Metro staff member on the phone and was told one of the girls took her cellphone from the seat where she left it and walked off the train. 

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"I don't care about the phone," Usanga said. "It's cheap. It's worthless. I want the SIM card. Everything I have of my son is on there. All the videos and pictures."

When asked why she reacted to the teens on the train, Usanga said the threats she heard them make struck a nerve. 

"My son got shot and killed in the crossfire because of the stupid arguments," Usanga said. 

Usanga said she believes the gun violence plaguing St. Louis has a lot do with young people not "communicating the right way". 

Usanga said she is desperate to have her photos and videos returned to her. She said she was hoping to make a slideshow of memories of Xavier for her daughters to have over the holidays. 

St. Louis Police confirm a call to the station for an assault. The department said it is working with MetroLink officers to get surveillance video because there were conflicting witness statements.

5 On Your Side reached out to MetroLink and is still waiting for a response. 

Xavier's case, like a majority of the children killed in the city this summer, is still under investigation.

RELATED: 13 cases remain unsolved

"CUT SHORT: Unsolved Killings of St. Louis Children" is an initiative of 5 On Your Side and its community outreach program, "Project 5," to raise awareness of the unchecked violence against children in the city of St. Louis from the summer of 2019 to present. For more information, click here.

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