Mark Zuckerberg and Snap CEO Evan Spiegel apologize to families of online harm victims at Senate hearing – as it happened

This live blog is now closed. For more on today's testimony, you can read:

• Full report - Social media CEOs testify on child sexual exploitation to US Congress

Family members of children who killed themselves after online sexual exploitation are attending the congressional hearing with portraits in hand.

The mood in the room is tense and somber. Dozens of family members of victims are in the audience, holding up their loved one's photos, hoping to catch the attention of the CEOs are they filed into the room flanked by staff. One woman quietly wept into her handkerchief. They have applauded senators' jibes at the tech CEOs multiple times.