A gunman acted alone when he shot and wounded a top US Republican politician and four other people on a baseball field in northern Virginia, the FBI has said.
James T Hodgkinson did not have any ties to terrorism, said Tim Slater, the special agent in charge of the Washington FBI office.
Representative Steve Scalise, the House majority whip, was gravely wounded in the shooting last week.
He has undergone several surgeries and remains in hospital.
His condition has been upgraded to serious.
Mr Scalise and other congressional Republicans were practising for their annual charity baseball game against Democrats when a gunman started shooting.
US Capitol Police and other officers returned fire and killed the gunman, who turned out to be an unemployed home inspector with a deep animosity towards President Donald Trump and other Republicans.
The gunman was identified as Hodgkinson, 66, who volunteered for Bernie Sanders's presidential campaign.
A female police officer with less than two years' experience withstood a barrage of gunfire from the gunman.
Alexandria police chief Michael Brown lauded the heroic actions of officer Nicole Battaglia and two other officers who were the first to arrive at the field.
Officers were first dispatched to the scene at 7.10am local time last Wednesday, Mr Brown said, and officer Kevin Jobe, a 16-year Alexandria police veteran, arrived less than two minutes later.
Ms Battaglia and another officer, Alexander Jensen, arrived at around the same time.