The Peoria County Coroner says 54-year-old Michael Robinson died after being shot in the chest.
It happened shortly before 10 p.m. in the 2200 block of West Starr.
Police responded to multiple shots fired in the back of the home. When they arrived, they found the men in the backyard.
A 54-year-old man was pronounced dead on the scene. The other victim, who lived at the home, was taken to OSF Saint Francis Medical Center. His injuries are not believed to be life threatening, according to authorities.
"We are still in the infancy of the investigation. I know that there was an altercation that occurred at the rear of the residence. And I don't know what caused it or circumstances behind. Still trying to figure that out," said Cpt. Mike Scally of Peoria police.
Police are looking for three suspects. This is the city's eleventh homicide of the year.