The two German Shepherds belonging to President Joe Biden and first lady Jill Biden were returned to the Biden family home in Delaware last week after aggressive behavior at the White House involving Major Biden, two sources with knowledge tell CNN.

Major, who was adopted by Biden in November 2018 from a Delaware animal shelter, had what one of the people described as a “biting incident” with a member of White House security.

The exact condition of the victim is unknown, however, the episode was serious enough that the dogs were subsequently moved to Wilmington, Delaware, where they remain.

CNN reached out to the White House for comment and did not immediately receive a reply.

Major, who is 3 years old, is the younger of the two Biden dogs, and has been known to display agitated behavior on multiple occasions, including jumping, barking, and “charging” at staff and security.