SAFETY HARBOR — About 20 minutes before Sierra Willson's pit bull attacked her sister and mother, the 22-year-old and the dog, Buster, were lying calmly in her bed.

"He loved cuddles," she said Saturday as she gazed down at a photo of them on her phone. She had taken it from bed the day before; it was time stamped 3:46 p.m.

At 4:07 p.m. Friday, the Pinellas County Sheriff's Office dispatched deputies and ambulances to the scene of a bloody dog attack at Willson's home.

Buster "turned" on his family, deputies said. Willson's mother, Heidi Cooper, 45, was still at Bayfront Health St. Petersburg on Saturday, covered with puncture wounds, lacerations and stitches. Willson's 14-year-old sister slept on the couch inside with her own set of stitches as her older sister — 8 months pregnant — stood outside the family home. Simba, another pet pit bull, bathed in the sun.

Buster was dead, his blood still staining the grass. Willson stabbed him. She was not injured, and doctors ensured the stress didn't affect her baby. Cooper, however, was badly bitten. But she's alive.

"That's what matters," Willson said, rubbing her bloodshot and teary eyes. "But he will be missed. He was an amazing dog."

Buster belonged to her brother, who recently shipped off in the Marines. The dog would have been 5 in March, but spent the first two years of his life with a negligent owner. He was rescued, Willson said, and spent much of his formative years locked in a crate.

He was the most dominant of the family's three pit bulls, territorial at times, but never vicious, she said. When he jumped off her bed Friday after they cuddled, she said he had a sudden burst of energy and ran toward her sister, Meaghan Tokay.

Despite deputy reports about the incident, Willson said the dogs were never in a fight with each other. Once she heard her sister and mother yelling at Buster, she quickly put Simba in the bathroom and her female pit bull Bleu in her crate.

When she rounded the corner into the hallway, she realized Buster wasn't just acting up, he was mauling her mother.

She didn't know what to do. Would pulling at him with teeth sunken in her mother's flesh worsen the wounds? She threw a water bottle at him to try to distract him. But he was consumed, she said.

"He's going to kill me," she recalled her mother crying.

That's when Willson went to the kitchen and grabbed a knife.

"It's like I blacked out," she said. "Killing him was not my intention ... but he wasn't letting go."

The dog's attack lasted 30 minutes, Willson said.

A wounded Buster finally calmed down and retreated outside. He tried to lie down with Meaghan as she was being treated by medics, but a deputy pulled him back.

He licked his wounds, lay down under a tree and died.

Willson said she's gotten Facebook messages harassing her, calling her a murderer. "I did what I had to," she said.

She doesn't know what in the dog "turned." He was good with kids, he loved to be petted and knew several trained commands, she said. She recalled him only ever having had spats with her other dogs, but nothing that ever worried the family.

She said she still loves the pit bull breed and hates that what happened will tarnish their already troubled reputation.

"I'd go out and adopt another one today if I could," she said.

Contact Sara DiNatale at sdinatale@tampabay.com. Follow @sara_dinatale.