Acting Attorney General Todd Blanche revealed Sunday that the alleged gunman accused in Saturday's White House Correspondents' Dinner shooting in Washington, D.C., appears to have traveled from Los Angeles through Chicago to the nation's capital by train."What we have learned and what they’ve learned just overnight is that it appears he traveled from Los Angeles through Chicago to Washington, D.C., and it appears he traveled by train during both legs of that trip," Blanche told Fox News's Shannon Bream on "Fox News Sunday.""The investigation is rapidly developing," he added.Authorities executed multiple search warrants overnight in Los Angeles and Washington, including at a hotel room where the suspect was staying, according to Blanche. Investigators are also reviewing devices and communications recovered during the searches.'TRAGEDY AVERTED' AT ATLANTA AIRPORT AS POLICE ARREST MAN WITH AR-15 ALLEGEDLY THREATENING TO 'SHOOT IT UP'"Law enforcement executed multiple search warrants last night, not only in Los Angeles but also in Washington, D.C., in the hotel room where the suspect was staying, and they executed search warrants on devices, and they’re going through that information right now," Blanche said.Blanche said investigators are still examining the motive, but early evidence suggests the suspect may have been targeting members of the Trump administration. He cautioned that the case remains in its early stages."As far as motivation, we are still looking into that," Blanche said. "It appears he was targeting members of the administration, but I say that generally because that’s all we know right now."TRUMP SAYS WOUNDED NATIONAL GUARDSMAN'S MOTHER HAS INSISTED TO HIM THAT HER SON WILL SURVIVE SHOOTINGBream asked whether the use of rail travel instead of flying may indicate an effort to avoid airport security records or TSA search. Blanche said authorities have not yet determined why the suspect chose the route."Why he did — that we don’t know at this point, but it could be the reasons you just described. It could be other reasons," Blanche said. "We don’t know whether he had the firearms with him."Blanche added that investigators believe the suspect purchased the firearms within the past several years, though authorities are still working to establish how the weapons were transported.WHO IS ANIBAL HERNANDEZ SANTANA, ACCUSED IN ABC STATION SHOOTING AND NOTE SAYING TRUMP OFFICIALS ARE 'NEXT'"It does appear that he purchased those firearms within the past couple of years," Blanche said. "That could be another reason why he traveled by train because he had the firearms with him, but I’m speculating there."Federal prosecutors are expected to pursue initial charges tied to firearm use during a violent crime and assault on a federal officer using a dangerous weapon, with additional charges possible as evidence develops."We don’t know what charges could come later. It depends on what evidence we develop," Blanche said. "But right now those two charges are the ones that we expect."Blanche also praised the response from security personnel and law enforcement agencies, saying they prevented the suspect from breaching the security perimeter near President Donald Trump."The reality is he didn’t really get past the perimeter," Blanche said. "That means law enforcement, Secret Service, the Metropolitan Police Department, the FBI did their jobs."