Angry that her parents demanded she break up with her boyfriend, a teenage girl helped kill her mother and two brothers during a grisly weekend ambush on the family's rural, wooded home, authorities said Sunday.

Investigators say a mother and her two sons were fatally shot and stabbed before their house was burned down in Alba, Texas, Saturday night. The husband and father, Terry Caffey, was shot in the head, but crawled 300 yards to a neighbor's while his house burned down.

The 16-year-old girl joined her boyfriend and two others in shooting and stabbing members of the Caffey family in their bedrooms before setting the house on fire, authorities said, confirming what most in this farming town had known since the pre-dawn attack Saturday.

The lone survivor was Terry Caffey, the father. He was shot five times - including twice in the back - before he dragged his bloodied body through the woods in search of help. He awaited surgery Sunday to remove the bullets, Rains County Sheriff David Traylor said.

Killed were Penny Caffey, 37, and sons Tyler, 8, and Mathew, 13.

"We feel confident that the motive was the fact that the juvenile daughter and one of the individuals in custody were dating and that the parents were attempting to break the relationship up," Traylor said, "which led to the crime that was committed."

The girl, who was not identified because of her age, was arraigned Sunday on three counts of capital murder and being held on $1.5 million bond. Charlie James Wilkinson, the girl's 19-year-old boyfriend, and two others were arraigned on the same charges.

Charles Allen Waid, 20, and Bobbi Gale Johnson, 18, were the others charged with three counts each of capital murder.

Waid, Johnson and Wilkinson were being held in Rains County jail on $1.5 million bond. The Caffeys' daugter was being held in neighboring Hunt County's juvenile detention center in Greenville. Traylor said he wasn't aware if they had attorneys yet.

The killings gripped everyone and everything in Emory, from the Sunday morning church services to lunch conversations at small cafes along the two-lane road running through this town of just 1,500.

Classmates of the Caffeys' daughter and Wilkinson described the couple as inseparable and with few other friends on campus. Stunning most here was the arrest of Johnson, who was widely described as a good student active in theater at Rains High School.

Jennifer McClanahan, a senior at Rains, said that Wilkinson had been scolded during her English class last week for being on the computer. Wilkinson, she said, in turn told the teacher that her girlfriend's father had hacked into his MySpace page.

McClanahan and others described Wilkinson as not really a troublemaker, other than constantly being told to remove the cowboy hat he always wore to school.

"That's Charlie," said McClanahan, 17. "He would start an argument over something like a hat."

Carl Johnson, a friend of the family, said the Caffeys moved about two years ago to just outside Emory. He called them good Christians and said he often told the daughter he wanted her soft singing voice to perform at his funeral.

"(The parents) didn't like the boy and were trying to break them up," Johnson said. "They told me at church they didn't have any use for him."

The attack occurred on about 20 acres of pine-canopied, remote land in Alba on a narrow gravel road with just two other homes. The area is so secluded that even the closest neighbors reported only faintly hearing what sound liked thunder early Saturday, and few saw the blaze.

Authorities said that Terry Caffey crawled 300 yards to his closest neighbor to get help, leaving a bloody trail. He was shot in the head, twice in the back and twice near his shoulder, Traylor said.

The Rev. Todd McGahee of Miracle Faith Baptist Church, where the Caffeys worshipped and were the house musicians, wept and struggled to stay composed during his Sunday sermon.

"When I first heard, I was like, I don't even think I would have crawled out of the house," McGahee told his congregation. "But God has a purpose for Terry's life. God has a reason. God gave him the strength to get out."

One gun and one knife were used in the attack, Traylor said. He would not detail which suspects he believed were responsible for which acts, saying only that all four were there at the time.

Police found the daughter hiding in the home of one of the suspects, Traylor said.

The family members were asleep in their bedrooms when the ambush began, Traylor said. Penny Caffey and Mathew suffered gunshots and stab wounds; the youngest, Tyler, had only stab wounds.

On the Caffeys' wooded plot, the family's black Labrador waited in vain by the ashes of the incinerated house and a burned van for his owners to return.

"There's been a change in this church and a change in this community," McGahee told about 80 worshippers. "And we can't just wish it away. ... It will be the same loss, the same hurt tomorrow. There's been that change in our lives."