CHICAGO -- Before Thursday night's dazzling fireworks display downtown, Chicago's Olympic committee aired a promotional video urging Chicagoans to support the city's Olympic bid.

Hours later, three people were shot, one fatally, as hundreds of thousands of people streamed out of Grant Park after the fireworks and the Taste of Chicago.

This is the third time in the last four years that gun violence has erupted at or near the Taste.

With the world's eyes on Chicago as a finalist for the 2016 Games, Chicago police held a press conference Friday to make clear the city can prevent violence at heavily attended events.

"I assure you we will do everything we can to keep this place safe for our visitors and our friends," Police Supt. Jody Weis said. "The safety at the Taste is undisputed."

Weis also stressed that the shootings happened a mile away from the Taste, not on the park grounds, which "was our focus." But police sources said there was an undeniable gang presence at the annual food fest Thursday. Many gang members openly flashed gang signs. The problem has grown worse in recent years, the source said.

Weis, while praising Thursday's "tremendous [police] coverage," promised even more officers on duty at Friday night's Navy Pier fireworks in response to the shootings. Uniformed and plainclothes officers would also attempt to move with packs of people as they left downtown. Police said late Friday there had been no major incidents after Friday's fireworks.

Investigators are trying to piece together what happened around 10:40 p.m. Thursday.

Reports suggest the violence stemmed from a clash of teenagers who knew each other. Police are investigating whether the shootings were gang-related.

Courtney Thomas, a 20-year-old Olive-Harvey College student, was fatally shot near Dearborn and Van Buren streets, police said. He was pronounced dead at 11:22 p.m.

"He was always an inspiration to somebody. I looked up to him,'' said Thomas' 18-year-old brother, Matthew Thomas.

Nearby, 15-year-old Deon Funches was grazed on the head by a bullet, and another male was shot in the buttocks. Both were treated and released.

Funches said he was trying to find the Red Line with friends when he heard people shouting gang slogans, then a gunshot. "Everybody ran," he said. "People were falling, getting stepped on and hiding behind chairs and bushes."

Police took one male into custody Thursday night after an officer saw him with a gun and chased him about a block, sources said. The gun was recovered by police.

No charges had been filed as of late Friday, and it's still unclear what sparked the shootings.

Investigators were reviewing surveillance footage from nearby CTA buses and other locations.

Copyright 2008, Chicago Sun-Times Inc.