Watch: Officials say Crimo planned attack, fired over 70 rounds into crowd at July 4th parade

HIGHLAND PARK, Illinois -- Officials say the person of interest in July 4th parade shooting pre-planned the attack for several weeks.

Deputy Chief Chris Covelli said that Robert “Bobby” E. Crimo III used a high-power rifle "similar to an AR-15," to fire over 70 high-power rounds.

Covelli said Crimo accessed the roof of a business via a fire escape ladder and that he was disguised in women's clothes. Investigators believed he did this to conceal his facial tattoos and help him during the escape. Crimo is believed to have worked alone. He is currently in custody.

Officials say the weapon was purchased legally by Crimo.

Covelli said the shooting left 6 dead and over 30 injured.