A Chicago man fatally shot his 22-year-old son after an argument over who would walk the dog erupted into a gunfight between them, say police.
The two men, who have not been identified, pulled firearms during an altercation in the Burnside neighbourhood on Sunday.
Both sustained multiple gunshot wounds and were taken to hospital, where the son was pronounced dead, police said.
The father, 43, was in a critical condition, according to authorities.
Police spokesman Anthony Guglielmi confirmed the fatal shootout in a tweet on Sunday.
Two weapons were recovered at the scene and police are investigating the incident.
Chicago is one of the most violent cities in the US, with more than 800 people shot so far this year, according to the Chicago Tribune.