The evacuation came as Israel, which said it was stepping up military operations against Hamas militants, announced it had found a 55-metre tunnel under the Al-Shifa hospital and released footage it said showed "hostages" inside the facility.
Johnson, who has endorsed former president Donald Trump's bid to recapture the White House in 2024, said the Capitol Hill security video would be posted in batches on a public website.
Meta, the parent company of Facebook and Instagram, has banned deepfakes since early 2020, with some exceptions for parody and satire. Other platforms have similar policies.