The executioners used a government-owned backhoe to dig shallow graves on a rugged hilltop. When authorities in the small town in the southern Philippines arrived at the scene, they used the same backhoe to dig up 57 bullet-riddled corpses, including those of 32 journalists and media workers.

The men and women had been en route to register an opposition candidate for an impending election—or, in the case of the journalists, to report on the politician’s candidacy. But before they made it to the election office they were stopped by a group of armed men, forced out of their vehicles, lined up and shot.

The Committee to Protect Journalists (CPJ) called it the single deadliest attack on the press in history.

On Thursday, more than 10 years after the massacre, a court in the Philippines found several members of a powerful political clan guilty in the attack.

The court in Quezon City outside Manila gave verdicts for almost 200 defendants charged with murder and other crimes. Former mayor Andal Ampatuan Jr. and his brother, Zaldy were found guilty and sentenced to life in prison for the mass murder in a remote town in the southern province of Maguindanao, according to Bloomberg. Several other family members were acquitted.

A number of police officers were among those convicted, according to ABS-CBN News.

Ampatuan Jr. was accused of leading the 2009 attack on the convoy of political rival Esmael Mangudadatu, who had announced plans to challenge the Ampatuans by running for governor of Maguindanao province.

Mangudadatu’s wife and two sisters were among the victims. Mangudadatu, who not traveling in the convoy for security reasons, survived the attack and is now a member of the Philippine House of Representatives.

The Ampatuans have denied the allegations and are expected to appeal the ruling, the Associated Press reported.

Activists applauded the long-awaited verdict, but called for further reforms in the Philippines, where politically motivated killings are common.

The “momentous verdict should help provide justice to the families of the victims, and build towards greater accountability for rights abuses in the country,” Phil Robertson, Deputy Asia Director of Human Rights Watch, said in a statement.

“More broadly, this verdict should prompt the country’s political leaders to finally act to end state support for ‘private armies’ and militias that promotes the political warlordism that gave rise to the Ampatuans,” Robertson said.

Philippine journalist Maria Ressa, the CEO of the news outlet Rappler, says the ruling sends an important message, especially given the political climate in the Philippines.

“I think today’s decision sends a warning: it may take time but impunity ends,” Ressa tells TIME.

“Remember, this was a gruesome mass murder committed by police at the order of politicians,” Ressa said. “I couldn’t help but see this against the drug war that human rights activists say has killed tens of thousands.”

Approximately 80 suspects remain at large, according to the AP. Some family members said they would not be satisfied until all of those responsible are brought to justice.

Mary Grace Morales lost her husband, a local newspaper reporter, and her sister, the newspaper’s publisher, in the attack. “What I can accept is a 100% conviction of all the accused,” she told the AP before the verdict. “An acquittal of even one of the principal suspects will be unacceptable.”

Read More: U.N. Experts Condemn Duterte’s ‘Incitement to Violence’ in the Philippines

In a statement on the verdict, the Defense Press Corps of the Philippines called for an end to violence against journalists: “The guilty verdict against the perpetrators of the Maguindanao Massacre must serve as a clarion cry against violence, harassment and oppression directed at society’s vanguards of truth — the fourth estate.”

Eighty-three journalists have been killed in the Philippines since the CPJ began collecting data in 1992. Three Philippine journalists were killed in 2019. The CPJ says the murders were likely perpetrated by agents working for local politicians.

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Write to Amy Gunia at amy.gunia@time.com.