Former President Barack Obama weighed in on March For Our Lives protests across the U.S. on Saturday, saying, “nothing can stand in the way of millions of voices calling for change,” as hundreds of thousands call for stricter gun laws.

Obama tweeted: “Michelle and I are so inspired by all the young people who made today’s march happen. Keep at it. You’re leading us forward. Nothing can stand in the way of millions of voices calling for change.”

MLK Jr.’s granddaughter Yolanda King and Noami Wadler, 11, wowed the crowd with their rousing speeches, with King saying, “I have a dream enough is enough.”

Hillary Clinton also weighed in: “Listening to the students from Parkland and across the country today is a reminder of what is possible when our future is in the right hands, and when we match inspiration with determination.”