The findings were reportedly made last week by a lawyer for Pence.
They will now be handed over to the federal police, the FBI, according to several sources.
An investigation has been launched with the Department of Justice's security division to evaluate the contents of the documents and find out how they ended up at the former vice president's residence in Carmel, Indiana.
The findings are serious for Republican Pence, who has repeatedly warned that he no longer has access to any classified information.
This is in response to questions asked after classified documents were found in a garage belonging to Joe Biden and which appear to have been stored there ever since his time as vice president.
Even at the home of Mike Pence's boss, former President Donald Trump, a large number of classified documents have been found during a search warrant ordered by the FBI.
The article is updated