Robert E Crimo, 21, has now been arrested after fleeing the parade route in the wealthy Chicago suburb of Highland Park, Illinois, U.S on Monday.
Lake County Major Crime Task Force Christopher Covelli said Crimo used his mother’s car to escape the scene and blended in with the community because he concealed his identity by wearing women’s clothing.
In a press conference, he said that Crimo remains in custody, and there are no indications he was acting with anyone else.
The shooter bought his gun legally, fired more than 70 rounds into the crowd from a roof left in women’s clothing to blend in the crowd afterwards, police said.
The motive for the shooting remains unknown, police said.
Dramatic footage showed toddlers in pushchairs, parents carrying babies, and the elderly who had set up deck chairs to watch the parade fled the gunfire for their lives.
“He started shooting again, and we ran behind the building and I put my son in a dumpster,” recalled one bystander.
“It was just horrible.”
Illinois’ lieutenant governor Juliana Stratton who says in a tweet: “Enough is enough.”
Stratton echoed the governor’s statement when he said gun violence was “our uniquely American plague”.
She added: “I’m angry too. We all should be.”
Highland Park’s Independence Day shooting killed six people and left at least three dozen others injured.