An Egyptian court has convicted four police officers in the killings of 37 detainees last summer, most of them supporters of ousted President Mohamed Morsi, and sentenced one to 10 years in prison.

The three others were handed suspended one-year terms in a misdemeanor court. All were convicted on manslaughter and negligence charges. The lawyer and families of the victims denounced the sentences as too light – arguing that the policemen should have been tried for murder.

The sentences were the first against officials for violations carried out during last summer’s crackdown on Morsi supporters that left more than 1,000 people dead. The democratically-elected president was ousted in July 2013.

The 37 men were killed after tear gas was fired into a van transporting them from a police station to a prison near Cairo on Aug. 18, 2013. Authorities at first said the detainees were trying to escape and had attacked their guards.

The gruesome incident drew international condemnation, and came just days after Egyptian security forces violently broke up two sit-ins in Cairo by Morsi supporters who had been protesting for weeks against his ouster. Hundreds died in the raids on the two camps and in street violence that engulfed Egypt in the following days. No charges have been made in connection with those raids.

Mohammed Abdel-Maaboud, one of eight surviving detainees who was locked in the back of the van for nearly nine hours when it was targeted with tear gas, dismissed Tuesday’s sentencing as a “farce.”

“How can someone who killed 37 people get only 10 years for negligence and manslaughter,” Abdel-Maaboud said from his hometown in the Delta province of Sharqia. “This can’t be a ruling. This is an indirect acquittal,” he told The Associated Press.

Osama el-Mahdi, a lawyer for the victims, said the prosecutor had only referred the case to a misdemeanor court – which is unable to hand down life sentences or the death penalty.

“On the surface of it, this is a verdict to calm public opinion. But on the other hand, it overlooks a more serious charge and more senior officials who are implicated,” he said, adding that he wanted to include more senior police officials in the case but was denied by judges.

Egypt’s official National Council for Human Rights said in a report this week that both police and armed protesters were responsible for the deaths of 628 people in violence that took place on Aug. 14, 2014. Amnesty International said more than 1,400 people have been killed since Morsi’s ouster – and thousands arrested. It has blamed security forces for using “excessive” force against protesters.

A report by The Associated Press released Sunday said Egypt’s crackdown on Morsi supporters and other opposition groups has resulted in the jailing of at least 16,000 people since July – representing the county’s largest round-up of anti-government activists in almost two decades.

Rights activists say reports of abuses in prison are mounting, with prisoners describing systematic beatings and miserable conditions with dozens packed into tiny cells.

The Egyptian government has not released official numbers for those arrested in the sweeps since Morsi was ousted, but four senior officials – two from the Interior Ministry and two from the military – gave the AP a count of 16,000. That includes about 3,000 top or mid-level members of Morsi’s base of support, the Muslim Brotherhood.

The Brotherhood, which has an estimated 800,000 members, has been a major target of the government since the military toppled Morsi. The group has largely gone underground, but is unlikely to disband as it has survived repression by one Egyptian autocrat after another.

Journalists critical of the new regime and other political opposition groups have also found themselves in the cross-hairs. In February, Egypt released a list of 20 journalists being pursued by authorities on “terrorism” charges.

Al Jazeera has nine employees on the list, including three already in detention. Journalists Baher Mohamed, Peter Greste and Mohammed Fahmy have been detained in Cairo since Dec. 29 while on assignment for Al Jazeera English.

Earlier this month, their trial was adjourned, again, until March 24 and the defendants remain in jail on charges of spreading false news and belonging to a “terrorist group,” referring to the Muslim Brotherhood.

A fourth Al Jazeera journalist, Abdullah al-Shami, has been detained for more than six months and has been on a hunger strike since Jan. 23.

Al Jazeera and wire services