A Massachusetts man was arrested Thursday evening near the White House and accused of revving his vehicle’s engine amid a crowd of demonstrators gathered ahead of President Biden’s State of the Union address.

The incident ended with police forcing the man to the ground at 16th and H streets NW. His alleged actions in the white Ford Mustang caused a brief scare among people demanding a permanent cease-fire in the Israel-Gaza war.

Authorities have not ascribed a possible motive, but during a D.C. Superior Court hearing Friday, officials unsealed an arrest affidavit alleging that 18-year-old Brandon G. Allen “proceeded to rev his … engine causing mass hysteria.”

A D.C. Superior Court magistrate judge ordered Allen, who lives in Franklin, Mass., released from jail and set a hearing for April 17. Charges filed against him include reckless driving, resisting arrest, making threats to do bodily harm and disorderly conduct.

Neither the prosecutor nor his attorney, Alvin Thomas Jr., discussed details of the case during the brief court hearing. Attempts to reach Allen were not successful on Friday. Thomas declined to comment when reached by phone.

The incident occurred during a night of demonstrations leading up and during Biden’s address at the U.S. Capitol. Dozens of protesters blocked Pennsylvania Avenue, and at one point spread a banner across an intersection.

About two dozen demonstrators wearing black T-shirts that read “Biden’s legacy = genocide” locked arms and held hands to form a chain to briefly block traffic. A second group of demonstrators sat down across Pennsylvania Avenue and unfurled a large green and white flag.

The incident involving Allen occurred shortly after 6 p.m. when he stopped the Mustang with Massachusetts license plates, at 16th and H streets. The affidavit quotes a witness saying the driver “accelerated his vehicle into the crowd.” The affidavit also says the driver parked his vehicle in the crowd, where he revved an engine.

Allen appeared to be getting out of the vehicle when police forced him to the ground and handcuffed him. The man was heard screaming, “I’m only 18 years old! I’m only 18 years old!” A D.C. police report says Allen “disobeyed multiple verbal commands from officers to get out of the vehicle.” The report says the man “forcefully tried to remove officers’ hands when being detained.”

Astrid Riecken contributed to this report.