Police are using tear gas and percussion grenades to begin clearing pro-Trump protesters from the grounds of the U.S. Capitol ahead of a curfew in Washington.

Police donned gas masks as they moved in Wednesday evening with force to clear protesters from the Capitol grounds shortly before a curfew took hold. In the moments before, there were violent clashes between the police and protesters, who tore railing for the inauguration scaffolding and threw it at the officers.

Police used tear gas and percussion grenades to break up the crowd, which began dispersing.

Dozens of supporters of President Donald Trump breached security perimeter and entered the Capitol as Congress was meeting, expected to vote to affirm Democrat Joe Biden’s presidential win. They were seen fighting with officers both inside the building and outside.

Police said at least one person was shot inside the Capitol; their condition was not immediately known.

The district’s police chief said at least 13 people were arrested, and five firearms had been recovered during the pro-Trump protests on Wednesday.