Seven marijuana activists were arrested in Washington, D.C. on Thursday while they were handing out free joints to Capitol Hill staffers as part of a campaign to push for laws that would allow D.C. to regulate marijuana.

Three of the activists were charged with possession with intent to distribute, the Capitol police said, while four other people were charged with possession. It is legal to possess, grow and give away small amounts of marijuana in the nation’s capitol, but it is illegal to do so under federal law.

The activists, who are members of marijuana advocacy group DCMJ, had organized an event called the “Congressional Joint Session” in honor of 4/20 to encourage Congress to end cannabis prohibition and allow D.C. to change its marijuana laws. Members of the group told DCist they chose the location of their demonstration — the corner of 1st Street and Constitution Avenue Northeast — because it is located near the Capitol building but is not federal land.

The arrests put an early end to the Congressional Joint Session, which had aimed to give out at least 1,000 joints. U.S. Capitol Police said in a statement that officers began arresting people around 12:15 p.m. after “after witnessing them distributing marijuana in public view to passersby.”

DMCJ has previously given weed away in public in D.C., including on Inauguration Day, when the group gave out thousands of joints without any arrests, according to DCist. Next week, DCMJ plans to smoke on the Capitol steps to push lawmakers to get rid of federal prohibitions on cannabis.

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Write to Abigail Abrams at abigail.abrams@time.com.