Lawmakers grilled the leaders of Facebook, Google and Twitter on Thursday about the connection between online disinformation and the Jan. 6 riot at the Capitol, causing Twitter’s chief executive to publicly admit for the first time that his product had played a role in the events that left five people dead.

When a Democratic lawmaker asked the executives to answer with a “yes” or a “no” whether the platforms bore some responsibility for the misinformation that had contributed to the riot, Jack Dorsey of Twitter said “yes.” Neither Mark Zuckerberg of Facebook nor Sundar Pichai of Google would answer the question directly.

The roughly five-hour hearing before a House committee marked the first time lawmakers directly questioned the chief executives regarding social media’s role in the January riot. The tech bosses were also peppered with questions about how their companies helped spread falsehoods around Covid-19 vaccines, enable racism and hurt children’s mental health.