The House select committee investigating the deadly Jan. 6 Capitol riot announced Thursday it issued subpoenas to four of former President Donald Trump’s closest allies late Thursday, including his former chief of staff Mark Meadows and his onetime close advisor Steve Bannon.

The subpoenas, which were also sent to former White House Deputy Chief of Staff for Communications Daniel Scavino and ex-Defense Department official Kashyap Patel, instruct the witnesses to produce materials and appear at depositions in the coming weeks, the committee said in a press release.

This subpoenas marks a dramatic escalation of the probe by the committee, which seeks to provide a complete analysis of Jan. 6, 2017, invasion in which thousands of Trump supporters drove Congress into hiding, temporarily stalling the confirmation of President Joe Biden’s win.

Rep. Bennie Thompson of Mississippi, who is the chair of the committee released a statement on Thursday.