Protests After Off-Duty Cop Kills Black Man in Chicago

— -- Dueling protests clashed on Sunday after an off-duty city of Chicago police officer shot and killed a 25-year-old black man.

Blue Lives Matter and Black Lives Matter demonstrations grew tense on Sunday afternoon as protesters shouted chants such as "KKK" and "CPD," near the site of a deadly shooting on Saturday that involved an off-duty police sergeant and a man visiting Chicago to attend a funeral, reports WLS, ABC's Chicago station.

Police investigators said Joshua Beal of Indianapolis was carrying a firearm when he was fatally shot on Saturday, but family members dispute the police narrative, WLS reports. A spokesman for the Chicago Police Department said the officer was fired on and returned fire.

"Nobody should have to sit there and witness their brother get killed by the same people who are supposed to protect us," said Beal's sister Cordney Boxley.

The victim was identified by family as Joshua Beal, a father of two. He was taken in critical condition to Advocate Christ Medical Center, where he died. He was in Chicago for a funeral

The shooting took place after a vehicle leaving funeral services at a nearby cemetery stopped in traffic in front of a Chicago fire house, police say. An off-duty firefighter told the driver that they were illegally blocking the fire lane. The occupants exited the vehicle and an altercation ensured, police said. An off-duty Chicago police officer inside a nearby business came out to assist the firefighter.

A Chicago police sergeant driving to work stopped when he observed a man with a firearm in his hands. After the man "failed to drop his weapon, shots were fired striking the individual multiple times," police said.

"Chicago police gunned my baby down like a vicious animal," said Tiffaney Boxley, Beal's mother. "They shot him twice in the back and three times in his front."

According to family, an off-duty officer in an unmarked vehicle cut off one of the vehicles in the funeral procession. The family members and officer got out of their vehicles. After a verbal exchange, gunfire erupted but Beal's family said that he did not provoke the officer, and merely disclosing that he had a concealed weapon permit.

A woman who said she was driving by as the fight escalated recorded cellphone video that captured the sounds of multiple gunshots.

"The man didn't pull a gun," said the woman, who declined to be identified. "The man was on the passenger side of the car."

The off-duty police officer and off-duty firefighter sustained non-life-threatening injuries.

The officers involved will be placed on routine administrative duties for 30 days, police said.

The Independent Police Review Authority is investigating.

ABC News' Brendan Rand contributed to this report.