Facebook CEO Mark Zuckerberg is facing rare public outrage from within his own company over inaction on incendiary remarks recently posted by President Donald Trump.

During a company-wide town hall, Zuckerberg struggled to explain his decision-making process as many of his employees, using a real-time feedback tool, reminded him of promises to remove content that calls for violence or that could lead to imminent physical harm.

“It’s crystal clear today that leadership refuses to stand with us,” Brandon Dail, an engineer at Facebook, tweeted as the town hall was taking place.

Another Facebook employee told CNN Business they found Zuckerberg’s answers to staff questions at the town hall lacking, and said the CEO risked alienating more of his staff rather than addressing their concerns.

Virtual walkout: Tuesday’s event follows days of employee activism. On Monday, some staffers staged a virtual walkout in protest.

At least one worker, software engineer Timothy Aveni, has quit his job, saying it is no longer feasible to “keep excusing Facebook’s behavior.”

Contrast with Twitter: Facebook’s silence on Trump’s tweets — which claimed Thursday that “when the looting starts, the shooting starts” — stands in stark contrast to Twitter, which marked Trump’s tweet as violating the platform’s rules on “glorifying violence.”

Earlier this week, Zuckerberg said that though Trump’s tweet provoked in him a “visceral negative reaction,” he felt Facebook was dedicated to “free expression.”