At a San Antonio Walmart, a man driving through the parking lot stopped his car when he saw another man grab a woman by the hair and begin punching her, San Antonio Police Chief William McManus told reporters, Reuters reported.
When the Good Samaritan shouted at the other man to leave the woman alone, 21-year-old Telles Juarez is accused of shooting him in the neck and killing him in the parking lot, McManus said.
A woman who was in the car with the man who tried to intervene was wounded by shrapnel and was hospitalized. A 31-year-old woman was hit by a stray bullet as she walked into the store several yards away and was in critical condition, McManus said. Police did not release the names of the victims.
McManus said Juarez jumped into his car to flee, but shoppers had already called authorities and a police helicopter was able to follow him for about 15 miles (24 km) until he was arrested without incident.
Police said Juarez would be charged with murder and aggravated assault.
"You have to give credit to the man for being willing to intervene," McManus said. "Unfortunately, this man was too eager to shoot."
The woman with Juarez was not seriously hurt, McManus said.
In New Jersey, authorities released few details about the shooting in the parking lot of the Hamilton Mall that claimed the life of a 21-year-old Atlantic City man. His 26-year-old brother was shot in the leg and was in stable condition, acting Atlantic County Prosecutor Diane Ruberton said in a statement.