Two men are on trial in the U.K., accused of killing one suspect’s ex-girlfriend's sister and the sister's three children in a revenge plot gone wrong.

They both pleaded not guilty to the charges.

In opening statements on Tuesday, Nov. 18., prosecutors argued before jurors that Sharaz Ali, 40, of Bradford, decided to "take revenge" on his ex-girlfriend Antonia Gawith, by setting fire to her house in Bradford in the early morning hours of Aug. 21, 2024, the BBC reports.

Antonia managed to escape, but her sister, Bryonie Gawith, 29, and her three young children, Denisty, 9 Oscar, 5, and Aubree Birtle, 22 months, were all killed in the blaze.

Ali and his friend, Calum Sunderland, 26, of Keighley, were each charged with four counts of murder, attempted murder and attempting to cause grievous bodily harm, police said.

Ali was allegedly "motivated by jealousy and fueled by drink and drugs" and "decided to take revenge on his ex-partner Antonia regardless of the potential consequences for others,” prosecutor David Brooke argued before jurors on day one of the trial on Tuesday, Nov. 18, according to the BBC.

Ali allegedly broke into the house just before 2 a.m. and poured gasoline inside the house and set it on fire, Brooke claimed.

Bryonie and her three children died in the "catastrophic" fire, he said.

Lindsay Pearson, 56, said her daughter heard yelling coming from the house at about 1.45am, The Guardian reports.

Shortly after, her daughter saw “a big flame, like the sky was all lit up,” adding, “It was like thunder and lightning, like you see in a thunderstorm.”

Ali was injured in the fire. "Caught by his own actions,” Ali had to be rescued from the blaze, Brooke told jurors.

Want to keep up with the latest crime coverage? Sign up for  PEOPLE's free True Crime newsletter for breaking crime news, ongoing trial coverage and details of intriguing unsolved cases.

Antonia had been in a relationship with Ali for seven years, Brooke told jurors, the BBC reports.

Tired of his alleged abuse and alcohol use, she left him and went to stay at her sister Bryonie’s house, Brooke said.

A third suspect, Mohammed Amjid Shabir, allegedly drove Ali and Sunderland to the house but died of a heart attack in jail while awaiting trial, the BBC reports.

If you are experiencing domestic violence, call the National Domestic Violence Hotline at 1-800-799-7233, or go to thehotline.org. All calls are toll-free and confidential. The hotline is available 24/7 in more than 170 languages.