PHOENIX - A family of five from Owasso is dead after Phoenix police say the family's oldest son violently turned on his parents and sisters.

It’s being called an "unspeakable tragedy.”

The Buckner family moved to Arizona after living in Owasso for several years.

Phoenix police say that Vic Buckner, his wife Kimberly, and their two daughters – 18-year-old Kailtlin and 6-year-old Emma –  were gunned down in their home early Tuesday morning.

The oldest son, 26-year-old Alex Buckner, was the shooter, investigators say.

Neighbors reported they heard an argument coming from the home shortly before they arrived and heard gunshots and Alex set the home on fire.

Police say, at that point, family members were still inside the home calling for help. Shortly after, those calls went silent.

"I heard things this morning and saw things that I haven’t seen in 30 years," Phoenix Police Sgt. Trent Crump said in a phone interview with News On 6.

Alex Bucker was later shot and killed by police.

Back in Owasso, friends of the Buckners are in shock.

No one wanted to talk with us on camera, but we did speak with a friend over the phone. They said Buckner had a troubled past but seemed to be getting better.

Owasso records show police arrested Alex Buckner twice in 2012 before he moved to Arizona with his family. He was arrested once for shoplifting, the other arrest was for drugs.

Reports say police found Alex passed out in front of a restaurant after using K2.

Friends say shortly after his arrests he claimed he'd found God and had stopped using drugs.

But they say Alex also had paranoid delusions and told friends the FBI was watching him and trying to hurt him.

They told News On 6 the family thought the move to Arizona would help get him back on track.

Now they’re left to wonder what led to such a tragic end for a family they knew as friendly and ordinary.