A Secret Service agent shot and critically wounded a man outside the White House Friday afternoon after he approached a guard booth carrying a small silver pistol and refused to put it down, according to law enforcement officials.

Lines of tourists were frantically ushered away from the area as heavily-armed police converged on the publicly accessible security shack near 17th and E streets Northwest. The White House was put on lockdown and Vice President Biden was secured inside the complex, authorities said. President Obama was golfing at Joint Base Andrews at the time.

Authorities said the man was shot once in the chest and was hospitalized in critical condition Friday night. Two law enforcement officials identified him as a Pennsylvania man in his mid-30s.

Police released no other details about him or an apparent motive. Authorities discovered ammunition for a .22 caliber weapon inside the man’s white sedan, which was parked near the scene, according to two law enforcement officials.

Friday’s apparent attempt to breach the White House grounds is the latest in an ongoing series of security incidents in recent years at or near the presidential complex. It took place against a backdrop of heightened global tension brought on by terrorist attacks and the ongoing wars in the Middle East and Afghanistan, and as officials were investigating the crash of an Egyptian passenger jet over the Mediterranean Sea.

Story and Picture: Courtesy Washington Post.