Two men have been given four life sentences each for murdering four children with petrol bombs as they slept in their beds.
Fuelled by drink and drugs, Zak Bolland and David Worrall filled two glass bottles with £1.50 of petrol bought from a local garage, stuffing the tops with tissue paper as they prepared the attack at 5am on December 11, Manchester Crown Court heard.
Bolland must serve a minimum of 40 years and Worrall 37 years.
After the kitchen window of Michelle Pearson's home was put through, two lit petrol bombs were thrown inside. Bolland hurled his bottle which "exploded" near the stairs, blocking the only exit to the ground floor and trapping the victims upstairs.
Within seconds flames engulfed the three-bedroom mid-terrace home on Jackson Street, Walkden, Greater Manchester.
Mrs Pearson, 36, woke up and screamed: "Not the kids! Not my kids!" and dialled 999, but she was overcome with heat and smoke before completing the call.
Demi Pearson, 15, her brother, Brandon, eight and sister, Lacie, seven, sleeping in a front bedroom, all died in the blaze.
Their severely injured mother was rescued with her youngest daughter, Lia, three, who died in hospital two days later.
Mrs Pearson's son Kyle, 17, had been involved in a "petty" feud with Bolland over damage to the defendant's £200 car, prompting a series of tit-for-tat attacks.
Kyle managed to escape with a friend, Bobby Harris.
Bolland, 23, was found guilty of four counts of murder and three of attempted murder.
Worrall was convicted of four counts of murder and three of attempted grievous bodily harm with intent.
Courtney Brierley, 20, Bolland's girlfriend at the time, was accused of encouraging the attack and was found guilty of four counts of manslaughter, but cleared of three counts of attempted murder.
She was sentenced to 21 years in prison.
Members of the Pearson family sitting in the public gallery hissed "Yes" as the guilty verdicts were delivered, following around 16 hours of deliberation by the jury.
In the dock, Worrall blinked hard and put his head down, Worrall sat looking straight ahead crying silently, while Brierley also wiped away tears.
They will be sentenced at 3.45pm.
Kyle saw the light from Demi's mobile phone at the window before she coughed in the thick smoke then appeared to fall away from the window.
CCTV shown to the jury showed Bolland and Worrall at the address at 4.55am for one minute and five seconds. The cameras recorded a flash then a larger second one from the petrol bombs, before they fled.
Neighbours ran out to help but were beaten back by the heat and flames as multiple 999 calls were made.
Three fire engines scrambled to the scene, the first arriving at 5.04am, with firefighters in breathing apparatus finding Brandon face down on his bedroom floor, as if trying to crawl out, and Lacie directly behind him, suggesting she was following her brother to try to escape.
Demi was found on a bunk bed, hands stretched out to the open window, and Lia was found in the bath.
As firemen battled the heat, smoke and flames to bring them out, a team of 15 paramedics worked on the mother and her children laid out on the snow-covered street.
Bolland and Kyle had been friends until the accused's Peugeot car was set on fire and his house windows smashed, around November 25 last year, about two weeks before the fatal attack, and he blamed the teenager.
The defendant demanded £500, sending harassing text messages, one demanding: "Fire letter box I want my my £500."
Bolland threatened to fire bomb Mrs Pearson's home, leading her to call police on November 26, and the fire service fitted a letter box cover.
But due to an "apparent misunderstanding" police took no action against Bolland for smashing windows at Mrs Pearson's home - and days later he was back gloating that he had escaped police action and taunting her with shouts of "Grass!"
Mrs Pearson again called police and asked for a restraining order, but two days before her children were murdered her bin was set on fire and the word "Grass" spray painted on her house.
Hours before the attack, Bolland and Worrall spent the night drinking before both made their first visit to Jackson Street around half past midnight on December 11, about four hours before the fire.
Worrall attacked the front door with a metal pole before Bolland threatened he would "Kill 'em all", before they left.
Police arrived and took a statement from Mrs Pearson, one officer checking on the youngsters upstairs, who were asleep.
Back at his mother's house two minutes' walk away, Bolland and Worrall became more aggressive as they snorted cocaine and drank lager before Bolland said: "Shall we do it?" and Worrall replied: "Yeah, I'll do it."
Arming themselves with an axe and a machete they got a frightened friend, Abigail Toone, to drive them to a Tesco garage for the petrol to be used in the attack.
Ms Toone drove them back to Bolland's home, where the two men went inside, emerging a few minutes later with the bottles.
Brierley gave the driver directions to an alley near the Pearson home where she told her boyfriend: "Do it quick Zak, hurry up," as the two men got out with the bottles.
Bolland and Brierley were arrested at around 6pm on the day of the fire, after contacting police, walking hand-in-hand to the officers who arrived to arrest them.
Worrall was arrested, "shaking profusely", the day after as he stepped out of the shower at his mother's house on Coronation Street, Salford.
Bolland admitted throwing the second petrol bomb but said he intended only to damage the house which he thought was not occupied.
"I heard like a big whoosh. I didn't look back," he told the jury.
He blamed Mrs Pearson's sons for an earlier attempt to torch his car, smash his windows and set fire to his mother's home.
Worrall said he thought they were only going to set fire to wheelie bins and denied throwing a petrol bomb.
Brierley said she did not know the two men had petrol bombs and claims Bolland had a "controlling influence" over her during their "toxic" relationship.
Mrs Pearson is still "very, very poorly" and there is a "serious risk" she may not survive if she catches an infection to her "dreadful" burns.