PHOENIX, Ariz. -- Family, friends and members of the South Phoenix community are mourning Monday night's shooting death of Luz "Estella" Navarro, 48.

Navarro was killed by a gunman in the parking lot of a Kmart store on Baseline Road and Third Street where she had been shopping.

"This tragic incident happened to an innocent and random victim," said Sgt. Andy Hill of the Phoenix Police Department.

Hill said Navarro had just brought her husband home from the hospital and was trying to catch up on chores when she was shot in the head in the apparent robbery attempt.

"We do know the suspects had been hanging around in the parking lot for some time," Hill said. "They had had contact with some people in that parking lot in the area by that store."

"If you want to use the word stalking or preparing or lying in wait for a victim, that's exactly what they were doing," Hill said.

Police are looking for the gunman and another person who drove off in a primer gray 1980s-model pickup and ask anyone who saw the incident or knows the suspects to call investigators.

"We believe they may do it again," Hill said. "They are on the loose and one of them or both of them may be armed so it's something we're very concerned about."

Navarro was a longtime volunteer at St. Catherine's Church in south Phoenix, where she taught catechism classes.

She leaves behind her husband of 23 years, a 20-year-old daughter and a 16-year-old son.