The man accused of opening fire on a Fourth of July parade in Chicago, leaving at least seven people killed and more than 30 others injured, has been charged with seven counts of first degree murder.
Suspect Robert E Crimo III surrendered to officers and was arrested hours after Monday's attack in the suburb of Highland Park, Illinois.
The 21-year-old was dressed in women's clothing to hide his facial tattoos, in a bid to blend in as he escaped the scene, police said.
Crimo fired into the crowd at random and had planned the attack for several weeks, according to authorities.
He is alleged to have climbed up a fire escape ladder on to the roof of a business before firing more than 70 rounds at the crowd with a high-powered AR-15-style assault rifle.
Among the dead were Nicholas Toledo, a grandfather from Mexico aged in his 70s who was celebrating Independence Day with his family at the parade, and Jacki Sundheim, a teacher at a nearby synagogue.
Lake County Major Crime Task Force spokesman Christopher Covelli said the suspect had been able to blend in with the crowd as he left the scene and headed for his mother's home nearby.
Crimo was arrested after his vehicle was spotted, and officers at the scene found a second rifle in his car, Mr Covelli said.
Officials said they did not know the motive for the shooting.
There have been 15 shootings this year in which four or more people have been killed, according to a database maintained by The Associated Press, USA Today, and Northeastern University.