SAN ANTONIO -- Police were seeking a suspect after a 6-year-old boy and three adults were shot in the parking lot of a popular San Antonio steakhouse.

San Antonio Police Chief William McManus says two of the adults' injuries are life-threatening. The boy was shot in the leg and is expected to survive.

McManus says all four victims are related and the adults are in their 20s.

Get Breaking News Delivered to Your Inbox

According to police, the shooting occurred 8:40 p.m. Sunday as the group waited outside the Texas Roadhouse, near Ingram Park Mall.

McManus said, "We do not believe that this shooting was random."

CBS San Antonio affiliate KENS-TV reports investigators think it was a family violence situation.

Police say the masked suspect opened fire about 15 feet from the front of the restaurant, emptying the magazine.

KENS says a semi-automatic handgun was used and one round penetrated the restaurant's wall.

The station adds that the suspect fled and neither the suspect nor any of the victims entered the restaurant.