WASHINGTON (AP) — The House panel investigating the riot at the U.S. Capitol issued sweeping document requests on Friday to social media companies, expanding the scope of its investigation as it seeks to examine the events leading to the Jan. 6 insurrection.

The requests were issued to technology giants, including Google, Twitter, Facebook, YouTube and TikTok, and also to Reddit, Parler, Telegram, 4chan, 8kun and other platforms.

The committee asked 15 companies to provide copies of any reviews, studies, reports or analysis about misinformation related to the 2020 election, foreign influence in the election, efforts to stop the election certification and “domestic violent extremists" associated with efforts to overturn the 2020 election, including the attack on the Capitol.

“We have received the request and look forward to continuing to work with the committee,” Facebook said in an emailed statement.

Google, which owns YouTube, also confirmed receipt of the letter and said it would work with Congress. "The events of January 6 were unprecedented and tragic, and Google and YouTube strongly condemn them. We’re committed to protecting our platforms from abuse, including by rigorously enforcing our policies for content related to the events of January 6,” the company said.

Twitter declined comment about the document request.

The requested documents are being sought in what is expected to be a lengthy, partisan and rancorous investigation into how the mob was able to infiltrate the Capitol and disrupt the certification of Democrat Joe Biden’s presidential victory, inflicting the most serious assault on Congress in two centuries.

Earlier this week, the committee sent out another request for documents from intelligence, law enforcement and other government agencies. The largest request so far was made to the National Archives for information on former President Donald Trump and his former team. Trump accused the committee of violating “long-standing legal principles of privilege.”

Committee members are also considering asking telecommunications companies to preserve phone records of several people, including members of Congress, to try to determine who knew what about the unfolding riot and when they knew it. With chants of “hang Mike Pence,” the rioters sent the then-vice president and members of Congress running for their lives, wounded dozens of police officers and did more than $1 million in damage.

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Associated Press writer Barbara Ortutay contributed to this story from San Francisco.