The FBI and the Justice Department's National Security Division have launched a review of the documents and how they ended up in Pence's possession.
Investigation Launched by the FBI and Justice Department
It still needs to be made clear what the documents are related to or their level of sensitivity or classification. Pence's team plans to notify Congress on Tuesday. Pence's lawyer immediately alerted the National Archives, informing the Justice Department. A lawyer for Pence said that the FBI requested to pick up the documents that evening, and Pence agreed.

Pence's Legal Team Cooperates with Investigation
Pence's legal team drove the boxes back to Washington, DC, and handed them over to the Archives to review the rest of the material for compliance with the Presidential Records Act. In a letter to the National Archives, Pence's representative to the Archives, Greg Jacob, wrote that a "small number of documents bearing classified markings" were inadvertently boxed and transported to the vice president's home.