On President Trump’s 100th day in office, thousands of climate activists descended on Washington, D.C., to send the president a message — climate change is real.

Demonstrators braved temperatures above the 90s Saturday to march down Pennsylvania Avenue, chanting “water is life” and “keep it in the soil, can’t drink oil!” The gathering, already a familiar sight during Trump’s nascent presidency, came together under the banner of the People’s Climate March.

Participants surrounded the White House complex and staged a choreographed sit-in, beating their chests 100 times to symbolize both the president’s time in office and the heartbeat of the environmental movement. Trump was in residence at the time.

The Sierra Club helped organize the event, which drew celebrities like Leonardo DiCaprio, former vice president Al Gore and climate and clean water activists like Mari Copeny, best known as Little Miss Flint.