By: Emily Birnbaum of the Hill

House lawmakers tasked with investigating the country's largest tech companies on Tuesday said they have received an initial round of documents from Apple, Facebook, Amazon and Google's parent company Alphabet to aid their probe.

The announcement came on Oct. 15, the deadline lawmakers had set to receive the slew of documents they requested from the companies last month.

"We have received initial submissions from Alphabet, Amazon, Apple and Facebook as part of our investigation," the lawmakers – including the top Democrat and Republican on the House Judiciary Committee – said in the statement.

The statement came from House Judiciary Committee Chairman Jerrold Nadler (D-N.Y.) and ranking member Rep. Doug Collins (R-Ga.) as well as the leaders of the panel's antitrust subcommittee, Reps. David Cicilline (D-R.I.) and Jim Sensenbrenner (R-Wis.).

"The committee will review all of the information received from the companies in order to help inform next steps," they said. "We will hold additional hearings, discussions and roundtables as our investigation continues."

The House Judiciary Committee also requested documents from more than 80 other companies as part of its probe into the digital marketplace, a source familiar with the matter confirmed to The Hill. The committee has also asked for those documents by this week.

Over the summer, the Judiciary Committee – which has jurisdiction over antitrust issues – announced a formal investigation into the power of Big Tech. The probe is focusing on whether the dominant technology firms unfairly wield their power to quash competitors and take advantage of users, who offer up reams of personal information in exchange for free services.

The committee has held several hearings about the issue over the past few months, hauling in representatives from companies including Facebook, Google and Apple. The companies have all denied that they function as monopolies or take advantage of their powerful market position in areas including social media and digital advertising.

In September, the leaders of the antitrust probe sent letters to Facebook, Google, Apple and Amazon requesting an enormous tranche of internal communications and records regarding the use of their market dominance.

The panel requested communications among each company’s executives, records that were handed over in past antitrust investigation and internal documents detailing their organizational structures.

As of Tuesday, the companies had only begun to offer some of the documents that the committee has requested.

Democrats have left open the possibility that they would subpoena the companies if they do not answer the committee's requests in a timely or forthcoming manner, though Republicans on the panel have balked at the possibility.

Last month, after a meeting with Facebook CEO Mark Zuckerberg in Nadler's personal office, Cicilline – the head of the antitrust subcommittee and leader of the investigation – told reporters that the tech executive has agreed to cooperate with the probe.

"I look forward to his cooperation," Cicilline said in September, noting the investigation will include "document requests, requests for information, participation in a number of different ways."