Facebook CEO Mark Zuckerberg appears to have taken a shot at Donald Trump in a speech Tuesday, though he didn't mention the Republican presidential front-runner by name.

"I hear fearful voices for building walls," Zuckerberg said in his keynote address to the Facebook Developer Conference in San Francisco. "Instead of building walls, we should build bridges."

"Instead of dividing people we can connect people. We do it one person at a time, one connection at a time. That's why I think the work we're doing together is more important than it has even been before," he said, according to the Guardian, before he went on to describe new technology projects his technology giant is spearheading.

Earlier this month, Trump released a memo outlining how Mexico would pay for the wall on its border with the United States, a proposal that has been at the center of his presidential campaign.

Zuckerberg is not the first person to criticize Trump's immigration rhetoric, either directly or indirectly. Numerous politicians and groups have spoken out against Trump's anti-Mexico comments.