WASHINGTON (AP) — House lawmakers investigating the market dominance of Big Tech are asking Google, Facebook, Amazon and Apple for a broad range of documents including internal communications.

Letters went out to the four companies on Friday from the leaders of the House Judiciary Committee and its subcommittee on antitrust, which has been conducting a sweeping antitrust investigation of the companies and their impact on competition and consumers.

The companies have said they'll cooperate fully with the congressional investigation.

The lawmakers set an Oct. 14 deadline for the companies to provide the documents.

Judiciary Committee Chairman Rep. Jerrold Nadler says the documents will help the committee understand "whether they are using their market power in ways that have harmed consumers and competition."

The Justice Department and the Federal Trade Commission are conducting competition investigations of the companies.