Updated May 10 at 8:34 p.m.

Environmental activists disrupted a joint session of the Massachusetts Legislature Wednesday with a protest pushing for a more aggressive state response to climate change.

Just after 11 a.m., as the House and Senate wrapped up the first session of this legislative cycle’s Constitutional Convention without engaging in any deliberation, about a dozen protesters from the groups Extinction Rebellion Boston and Scientist Rebellion rushed to unfurl a banner with the message “No new fossil fuel infrastructure” in the front row of the gallery overlooking the House floor. The banner was quickly pulled away by a court officer.

Members of the group also began reading from a memorandum detailing their demands, which also include halting any fossil fuel infrastructure projects that are currently underway and additional steps aimed at creating what they call a "just transition" to a carbon-free economy.

The protesters remained in the House Gallery after the reading. Susan Lemont, a spokesperson for the activists who was stationed outside the room, said they would only leave if legislation banning new fossil-fuel infrastructure was introduced. At 5 p.m., when the State House officially closed, nine of them were arrested on trespassing charges.

Prior to the protest, one of the organizers, Alex Chambers, said a ban on new fossil fuel infrastructure would help the state meet aggressive emissions goals that are already on the books — and that the protest itself was aimed at disrupting a dangerous sense of complacency on the part of state lawmakers.

"Where we're at right now is, there's [a] ten-municipality pilot program that would let local municipalities opt into banning gas hookups for [new] commercial and residential usage," Chambers said. "And we're trying to go a step beyond that ... We want there to be an end date for all of this stuff.

"We want people to be aware that the Massachusetts government does not really have a plan for getting rid of new fossil fuel infrastructure, and for getting us off of gas," Chambers added. "And that should be alarming to people ...the state's own law binds us by certain targets, and yet we don't actually have a plan to meet these targets."

Wednesday's protest was the latest in a growing list of attention-getting actions conducted by Extinction Rebellion Boston, including blocking then-Governor Charlie Baker's driveway in September 2021, stopping traffic in the Seaport last fall, and occupying Governor Maura Healey's office in February.

Asked if Wednesday’s protest might be counterproductive, and make lawmakers less likely to ponder the steps suggested by the activists involved, Lemont cast the group’s tactics as a result of statis on the issues they care most about.

“It’s our job to push at them to push them, because we have all the other climate activist groups working with them,” Lemont said. “We’re sort of calling them out because there’s been no movement whatsoever."

This story was updated with news of the protesters’ arrests.