Image copyright AP Image caption The White House was placed on security alert

The Secret Service has shot an armed man outside the White House, according to US officials.

Police told ABC News that a man brandished a weapon at a security checkpoint near the building and was shot in the stomach.

The White House was briefly placed on lockdown after the shooting on Friday. President Barack Obama was playing golf in Maryland at the time.

The man was transported to hospital with critical injuries, officials said.

Vice-President Joe Biden was in the White House at the time. He was taken to a "secure area" during the incident, White House officials said.

"Secret Service Uniformed Division Officers gave numerous verbal commands for the subject to stop and drop the firearm," security agencies said in a joint statement.

"When the subject failed to comply with the verbal commands, he was shot once by a Secret Service agent and taken into custody

"At this time, based on a preliminary investigation, there is no known nexus to terrorism."

Image copyright AP Image caption An armed man was shot by a Secret Service officer

The White House has seen a number of security incidents in recent years, prompting changes at the executive complex.

In April, Secret Service caught an intruder climbing over the White House fence.

In 2014, Iraq War veteran Omar Gonzalez jumped the White House fence and ran into the building with a knife. Also that year, a toddler squeezed through the gates of the fence and was caught on the lawn.

In 2013, one man tried to crash a jeep filled with knives and bullets into a security gate.

In 2011, Oscar Ortega-Hernandez shot at the White House and was charged with attempting to assassinate Mr Obama or a member of his staff.

Mr Ortega-Hernandez believed God had given him a personal mission to attack the White House, law enforcement sources said.