A week after an Illinois man shot a top Republican in Congress and wounded several others, law enforcement officials said the investigation has found that the gunman acted alone when he fired dozens of bullets at lawmakers gathered for a Republican baseball practice, and that no links to any wider plot had been found by the FBI.

"At this time, the FBI has assessed that the deceased shooter, James Thomas Hodgkinson, acted alone," said Timothy Vale, a top official in the FBI's Washington, D.C. Field Office.

"We also assess that there was no nexus to terrorism," Vale told reporters at a news conference, saying for now, the investigation was simply focused on the gunfire that wounded Rep. Steve Scalise (R-LA), two U.S. Capitol Police officers, and two others who were helping lawmakers get ready for an annual charity baseball game.

"While the shooter was not known to have a history of diagnosed mental illness, he is known or was known to have an anger management problem," said Timothy Slater, Special Agent in Charge of the FBI Washington Field Office.

Slater said Hodgkinson had come to the Washington area in March of this year, and was living out of his vehicle, mainly in the parking lot of a YMCA near the baseball field.

Investigators did find a list of lawmaker names that had been put together by the gunman, but there was no evidence to suggest that it was some kind of 'hit list' or part of a broader plan to target individual members of Congress.

On Capitol Hill today, Republicans were wearing yellow and purple fleur-de-lis stickers to honor Scalise, whose condition was upgraded to fair condition.

"Congressman Steve Scalise continues to make good progress," read a statement issued by MedStar Washington Hospital Center. "He is now listed in fair condition and is beginning an extended period of healing and rehabilitation."