Full of fresh ideas and renewed faith, 15 members of a small Cobb County church headed home following a three-day conference in Florida. But hours into the return trip home, the group faced the ultimate test of faith.

Shortly after 4 a.m. Sunday, the two church vans in which they were riding were caught up in a horrific string of crashes on I-75 near Gainesville. The smoke-filled, foggy darkness made it nearly impossible to see, according to witnesses.

Of the 10 people killed in the wrecks, five were in one of the church vans: Pastor Jose Carmo; his wife, Adriana Carmo; their 17-year-old daughter Leticia; Jose’s brother Edsom Carmo; and his brother’s girlfriend, Rose.

The Carmos' other daughter, Lidiane, 15, was critically injured. Other members of the Church of the Restoration, on South Marietta Parkway in Marietta, suffered minor injuries.

“We need prayers,” Rosana Alves, a family friend and church member, told The Atlanta Journal-Constitution.

In Florida, questions grew as the human toll became clear. Florida police had previously closed the stretch of I-75 for about three hours the night of the wrecks because of poor visibility due to a mix of fog and heavy smoke from a brush fire that may have been intentionally set.

The highway was reopened shortly before 4 a.m. Sunday. But within the hour, at least a dozen passenger vehicles and six tractor-trailers were part of charred wreckage spanning a mile on both sides of the interstate.

Steven R. Camps and some friends were driving home hours before dawn when they were suddenly drawn into the massive wreck.

“You could hear cars hitting each other,” the Gainesville man told the Associated Press. “People were crying. People were screaming. It was crazy. ... If I could give you an idea of what it looked like, I would say it looked like the end of the world.”

When rescuers first arrived, the smoke and fog were so thick the only way they could locate victims was by following the sound of their screams and moans from the wreckage, which was strewn for nearly a mile.

Monday afternoon, a spokesman for the Florida Highway Patrol defended troopers’ decision to reopen the interstate and how they handled the crashes, which remain under investigation. The National Transportation Safety Board was considering whether to also investigate.

The fire that contributed to poor visibility on the highway had destroyed 62 acres and was still burning Monday. A Florida Forest Service spokeswoman said the fire began Saturday and investigators were still trying to determine whether the blaze had been intentionally set. She said there were no controlled burns in the area and no lightning.

At the Carmo family home near Kennesaw, Alves and another family friend gathered with a relative Monday, offering comfort to each other while remembering the friends and relatives taken from them in an instant.

Jose and Adriana Carmo, Alves said, were Brazilian natives. Since moving to the United States 12 years ago, they had become leaders of a group of other immigrants from the country. Two years ago, the Carmos left their jobs to devote themselves to the church Jose Carmo helped found.

“They were leading by faith,” Alves said. “They loved the work, the work for God. They loved reaching people and talking about God.”

The Carmos were more than just spiritual leaders, according to friends. In addition to having two teenage daughters of their own, the Carmos served as the “parents” of other Brazilian immigrants.

“She was my friend, my mentor, my mom, my everything,” Barbara Almeida said of Adriana Carmo.

Two years apart in age, Leticia and Lidiane Carmo were extremely close, Alves said. Both attended Sprayberry High School, danced together at church and also took music lessons together.

But the sisters’ personalities are evident even in photographs. At 17, Leticia Carmo was the outgoing one, dreaming about the prom and posing elegantly in snapshots. “She was like a princess,” Alves said.

Lidiane, who turned 15 in December, was the quieter of the two, friends said. Now, her loved ones are praying she survives her injuries, which include several broken bones and internal bleeding.

After learning of the crash, an uncle drove to Florida to be with her in the hospital. Once she is well enough, the family hopes she can be moved to an Atlanta hospital.

But late Monday, Lidiane was sedated, unaware she was the only survivor of her immediate family. Her uncle, Edsom Carmo, and his girlfriend, Rose, who lived in Woodstock, were also killed and each leave behind children, Alves said.

Another aunt, Luciane Boutin, said she and her husband have two young children of their own, but they are prepared to welcome Lidiane into their home.

If possible, family and friends would like to send the Carmo family members back to Brazil for burials. But Alves said that may not be possible because of the cost. Anyone wanting to assist the family can donate to the Carmo Family Funeral Fund at any Bank of America, Alves said.

Although the friends say they are devastated by the deaths, they remain strong in their faith, vowing to support each other in the days ahead.

“We are sad for us,” Almeida said. “But they are in a happy place.”

-- Staff writers Mike Morris and Curtis Compton and The Associated Press contributed to this article.