Photo courtesy of South Tucson P

Police are looking for a suspect in one of two South Tucson shootings on Sunday.

Four men were injured in the unrelated shootings.

The first shooting happened just before 4 p.m. in the 1800 block of South Eighth Avenue, near West 29th Street, during an argument between two men, said Lt. Jeff Inorio, a spokesman for the South Tucson Police Department.

Robert Robinson, 29, is suspected of firing several shots from a small-caliber gun that struck a 32-year-old man in the leg, Inorio said.

The victim fired back at Robinson, but police do not believe he was injured. Police have not found Robinson.

He is described as 6 feet 4 inches tall and weighing 300 pounds.

"Robinson should be considered armed and dangerous," Inorio said in a news release.

The second shooting happened around 9:45 p.m. in the 100 block of West 32nd Street, near South Eighth Avenue, Inorio said.

A 25-year-old man was shot several times in his torso and is in critical condition but is expected to survive, Inorio said.

A 53-year-old man and his 30-year-old son were also shot and had injuries that were not considered life-threatening, Inorio said.

Detectives determined the men were in the front yard of the home when the 25-year-old man brandished a weapon and threatened to shoot everyone, which prompted the 53-year-old man to draw his own gun and fire at the man, who then shot back, Inorio said.

Anyone with information about the shootings or about Robinson's whereabouts is asked to call 911 or 88-CRIME.