Friday’s uncontrolled spread of horrific videos — a propaganda coup for those espousing hateful ideologies — also raised questions about whether social media can be made safer without undermining business models that rely on the speed and volume of content uploaded by users worldwide. In Washington and Silicon Valley, the incident crystallized growing concerns about the extent to which government and market forces have failed to check the power of social media.

“It’s an uncontrollable digital Frankenstein,” said Tristan Harris, a former Google design ethicist and co-founder of the Center for Humane Technology.

Those pushing videos of Friday’s attack made small alterations — such as changing the color tones or length — of the shooting video originally live-streamed by the alleged killer himself through his Facebook page. Such tricks often were enough to evade detection by artificial-intelligence systems designed by some of the world’s most technologically advanced companies to block such content.