A gunman opened fire in a suburb of Chicago during the celebrations of the National Day. A day after the massacre, another person succumbed to his injuries. Meanwhile, investigators are still looking feverishly for a motive.

The death toll has risen to seven after deadly shooting at a holiday parade in the United States. One person died a day after the attack, Lake County Coroner Jennifer Banek said. The six other men and women killed were between the ages of 35 and 88 and all but one were from Highland Park. A gunman opened fire in the Chicago suburb on Monday, the American National Day. The alleged perpetrator was caught hours after the crime.

As the police later announced, the man fired around 70 shots seemingly indiscriminately into the crowd from a roof with what was initially believed to be a legally acquired gun. More than 30 people were injured.

The investigators are convinced that the shooter had been preparing his bloody deed for weeks. The 21-year-old disguised himself as a woman to disguise his identity and make it easier to flee, a police spokesman said. He got to the roof of a commercial building via a fire escape. From there he fired more than 70 shots. He then climbed down from the roof, dropped his rifle and mingled with the crowd of fleeing people. Hours later, he was arrested after a chase in his mother’s car.

Investigators say they have no clues as to a motive. Nothing indicates that the man was racially, religiously or politically motivated in his act, said Covelli. The authorities are investigating posts and videos that the 21-year-old had published on the Internet. According to the Chicago Tribune, the video includes a drawing of a shooter and people being shot, along with the caption, “I just have to do it” and “It’s my destiny. Nothing can stop me, not even me even.”