U.S. federal prosecutors have laid charges against a Minnesota man accused of throwing a liquid on Democratic Congresswoman Ilhan Omar during a public event in Minneapolis earlier this week, an incident authorities are treating as an assault on a sitting lawmaker.

Court documents filed by the U.S. Justice Department say Anthony Kazmierczak was arrested following the incident and is charged with forcibly assaulting, opposing, impeding and intimidating a member of Congress while she was performing official duties.

According to a sworn affidavit, investigators later determined the substance sprayed on Omar was a mixture of water and apple cider vinegar. Omar was not seriously injured, but the disruption prompted a security response and renewed concerns about the safety of elected officials.

Federal filings also note that Kazmierczak has a prior criminal record and had posted political content online supportive of U.S. President Donald Trump. Authorities have not alleged that the act was part of an organized group or broader plot.

The case comes as lawmakers across the United States continue to report heightened threats and harassment at public events, raising questions about political polarization and security for public officials. Similar incidents in recent years have led to increased calls for stronger protections for elected representatives.