At least six people are dead following a shooting at a July Fourth parade in Highland Park, Ill., according to officials.

The Lake County Sheriff's Office tweeted that the suspect was described as being a white male between 18 to 20 years old, with long black hair and a small build. He was wearing a white or blue T-shirt.

Law enforcement, including federal partners, remain on the scene searching for the suspect.

Law enforcement officials said the suspect appeared to be shooting from a rooftop, and that a rifle has been recovered at the scene.

During a news conference Monday afternoon, Highland Park police commander Chris O'Neill said the incident started at 10:14 a.m. local time.