Reports of an active shooter at the military base outside Washington used by Air Force One and other VIP aircraft turned out to be a false alarm on Thursday, briefly delaying a trip by Vice President Joseph R. Biden Jr.  

The all-clear at Joint Base Andrews — with the exception of a medical facility — was given about an hour and a half after the initial reports at 9 a.m., according to a tweet from the base’s account.  

The lockdown coincided with a planned active shooter drill at the busy facility, which is about 20 minutes outside of the nation’s capital and hosts aircraft used by the president and vice president and members of Congress.

Base officials later explained that a no-notice active shooter exercise was scheduled for later in the morning, but that someone misidentified a Security Forces emergency services team that was conducting a routine inspection of the base medical facility and called security.

“Fortunately, this was not a life-threatening situation,” Col. Brad Hoagland, 11th Wing and Andrews commander, said. “We take all threats seriously and reacted to ensure the security of those on the base.”

Biden was scheduled to depart for Ohio but was held at his home at the Naval Observatory in Washington, an aide said. He left later in the day to campaign for former Ohio Gov. Ted Strickland, who’s running against Republican Sen. Rob Portman.  

Separately, Homeland Security Secretary Jeh Johnson was testifying at a raucous Senate Judiciary hearing when he abruptly left the room, saying that “an unfolding situation” at the base would force him to “take a break.”  

The announcement came after the hearing was disrupted by a group of protesters who began standing one by one to protest deportations. Many of them chanted, “Jeh Johnson, you have blood on your hands” and “Not one more deportation.”   

Johnson returned around 10:30 a.m.