A man was shot outside the White House grounds after approaching a checkpoint with a gun and refusing commands to drop it, officials said. The White House was placed on lockdown after the shooting near 17th and E streets. The shooting occurred at around 3:06 p.m., law enforcement officials said. The man who was shot was identified by law enforcement officials as Jesse Olivieri from Ashland, Pennsylvania. The officials said Olivieri said he wanted to die and the incident was likely an attempt at suicide by cop. Olivieri will likely be charged with assaulting a federal officer, the officials said. "He was carrying a gun — it was a silver gun in clear sight, walked through the fence line," said Larry Samples, who was on E and witnessed the shooting. "They immediately tried to stop him and came up to him," Samples said. "[Authorities] yelled multiple times 'stop, stop, stop.' He kept ignoring them." Olivieri, who has been described as a white male in his early 30s, was shot in the chest by a Secret Service agent, law enforcement officials said. A weapon was recovered, officials said. D.C. Fire and EMS said Olivieri was transported to a hospital in critical condition. Rohail Khan, who said he was around 5 feet from the shooting, said he heard a single shot and then Secret Service yelled for everyone to get down. Olivieri was allegedly brandishing the gun and shot after refusing several commands to drop it. No one else was hurt. Samples described him as around 5 feet, 10 inches tall with shaggy blonde hair. "I saw the Secret Service and officers coming around him," Samples said. "They surrounded him. They gave him multiple chances to stop his advance and he refused. He just kept walking. He had a gun in plain sight." President Barack Obama was not at the White House. He has been notified of the situation, a White House official said. He was headed back to the White House after an afternoon of golfing at about 6 p.m. Government sources said two Secret Service officers had eyes on Olivieri before he even pulled out the gun and had "shadowed" him. He was never inside the White House complex. Washington, D.C., Metropolitan police will investigate the shooting, and the FBI will look into Olivieri's background, according to law enforcement officials. Taylor Cates was outside of the White House with her boyfriend when she spotted a man with the gun. "It wasn't even hidden, wasn't anything," Cates said. "He looked at me and kept walking." She and her boyfriend and three other people nearby stopped, unsure what to do and afraid of getting any closer. She said the man weaved through a few crowds and approached the security gate. "He had no facial expression at all," Cates said. "It was honestly terrifying," she said. Park Police and Secret Service officers searched the Olivieri's car, parked a few blocks away. He was taken to George Washington University Hospital. The White House lockdown was lifted by 4 p.m. The Secret Service announced last year that it would be adding "temporary security enhancements" to the White House, including an anti-climb feature with sharp metal spikes on top of the fence surrounding the grounds, after a series of high-profile incidents. In September of 2014, a man scaled the White House fence and made it all the way into the East Room before he was tackled and arrested. Omar Gonzalez, 43, pleaded guilty to charges related to the breach and was sentenced to nearly 1 1/2 years in prison. Prosecutors said he has a history with law enforcement where he described having "paranoid delusions." Jim Miklaszewski also contributed to this report. This story originally appeared on NBCNews.com.