Leaders of the Mountain Avenue Church of Christ in Tucson, Arizona, say it is unclear if church members Dorwan and Mavy Stoddard went to the Safeway supermarket near their home Saturday morning to buy groceries or to see Democrat Representative Gabrielle Giffords, who was meeting with voters.

According to a report from the Christian Chronicle, the official news blog of the international newspaper for the Churches of Christ, this much is known.

The Stoddards - described as "the lifeblood" of the 120-member congregation - were among the shooting victims when a gunman opened fire outside the store.

The Democratic congressman was shot in the head and listed in critical condition. Six other people - including Stoddard - were killed in the rampage, according to church leaders and news reports.

Stoddard "has gone to be with the Lord", said Bobby Valentine, pulpit minister of the Palo Verde Church of Christ in Tucson.

The Christian Chronicle said Stoddard's wife, Mavy, suffered three gunshot wounds to her legs and is in stable condition, leaders said.

"They were active members in the church. It's a big tragedy," said Valentine, who knew the couple through a Bible camp board and joint activities between the two congregations. "Prayers are the biggest thing right at the moment. I don't know any details in terms of the services."

The Christian Chronicle reported that Jessica Knapp, who works with the youth group at the Mountain Avenue church, said Stoddard tried to protect his wife during the rampage and was hit in the head.

"He got on top of her and tried to shield her," said Knapp, relaying information from church secretary Jody Nowak. Nowak and her husband, Mike, the church's minister, called Knapp from the hospital where Mavy Stoddard was being treated.

Chronicle reader Teresa Russell Nystrom wrote on the newspaper's Facebook fan page, "Dorwan and Mavy have worked on benevolence at MACC for years. They put their hearts into helping others that goes far beyond buying groceries. They have changed lives."

Knapp, a Mountain Avenue member for about 11 years, described the Stoddards as "the lifeblood of our church".

"This is going to be a huge hole in our congregation," the Christian Chronicle reported Knapp as saying.

"They were our benevolence committee," she said of the Stoddards. "They did the job fantastically. Instead of just writing checks, they would go meet with people and find out what was going on in their lives and what their needs were."

If there was a men's work day at church, Stoddard didn't just show up; he organised it, Knapp said. "If the baptistry was leaking, we called Dorwan," she added.

The Christian Chronicle said the Arizona Daily Star interviewed Mike Nowak, the couple's minister at Mountain Avenue Church of Christ. He said Stoddard was "a terrific guy, a jack-of-all-trades".

Stoddard performed maintenance work at the church; he and Mavy spent their summers travelling. Friends said they visited all 50 states and 28 foreign countries during their trips