Nico Jochnick shared a video on Tuesday of a U.S. Park police officer arresting his friend by pinning the teen’s head under his crotch while handcuffing him on the ground.

The person being detained is 17-year-old Elton Smole, a senior at Woodrow Wilson High School, who was participating in a student-led protest against President-elect Donald Trump, according to Washingtonian, which first reported the arrest.

Smole told Washingtonian that the incident was sparked after he drew a peace sign on an electrical box on the National Mall. Jochnick shows the image in the video. Smole said the officer “ran into him with a motorcycle, threw him to the ground, and sat on his face while making the arrest.” It happened around 3 p.m. near 17th St. and Constitution Avenue NW.

Thousands of D.C. high school students participated in the protest on Tuesday. “As [high school] students we don’t get to vote but we’re going to be suffering the greatest consequences of what’s happened in this election,” Jochnick told a WUSA9 reporter at the time. “So this is our way to unite, to come together, to show our voice, and really play a part in a country that we really desperately want to be proud of but that we’re having a difficult time of doing right now.”

Police charged Smole with vandalism and defacing public property, Anna Rose, spokesperson for the National Park Service, told DCist. However, the charges were dropped because he’s a first-time offender and agreed to participate in a program under the Metropolitan Police Department’s juvenile detention center.

The U.S. Park Police is also investigating the incident in regard to the officer’s use of force, which is done in all arrest cases, Rose said.