A small group gathered at Five Corners Friday evening to mourn the latest school shooting in Santa Fe, Tex. As people came and went, the number of demonstrators consistently hovered around 10­—the same number of people killed at Santa Fe high school hours earlier.

Among other messages, their signs said “Enough,” and “Policy change, not thoughts and prayers.”

“What happened?” one driver called out from the passenger window of his car as he pulled up to the intersection.

“Another school shooting. In Texas. Ten people killed,” replied Maria Black, who organized the gathering.

The driver paused as the news sunk in, then shook his head in disappointment.

“That’s how I feel,” said Keith Chatinover, the charter school senior who organized the trip to Washington, D.C., to protest gun violence earlier this month. He found out about today’s shooting on a morning news alert on his phone.

“Partly demoralized, partly desensitized. It’s a hard emotion to describe because it’s not an emotion you should ever feel,” he said.

Mr. Chatinover will travel to Boston Saturday to receive the Massachusetts high school Democrats activist of the year award for his work.

Ms. Black said she wants to have a collaborative conversation with gun owners to find solutions. “Let’s put some processes in place,” she said.

As far as why they gathered, Ms. Black said they had to do something. “We’re one little drop, but all these drops together form an ocean.”