An investigative journalist has reported that security forces executed at least 16 unarmed civilians during a confrontation in the western state of Michoacan in January.

The report, which was presented by Mexican journalist Laura Castellanos, puts into doubt the government’s claim that members of the civilian vigilante group  died after firing on the federal police in the city of Apatzingan. Three major media outlets, Univision, Proceso and Aristegui Noticias have published the findings, which were based on the testimony of 39 people, as well as video and images captured by bystanders.

“All of the witnesses, the survivors, the prisoners and the wounded, even hospital staff, incriminated the federal police,” Castellanos said.

After publishing the report, the website for Aristegui Noticias, linked to award-winning journalist Carmen Aristegui, was brought down by cyber-attacks, presumably carried out by government sympathizers.

The confrontation on January 6 stemmed from the occupation of the city hall by protesters angry about the government decision to dissolve the security force, G250. Members and sympathizers of the group had been occupying the building since December.

While then-Michoacan Federal Security Commissioner Alfredo Castillo maintained that the police convoy came under fire first, video and eyewitness evidence indicates that the occupiers carried no more than six pistols between the group of more than 100.

A second attack took place a little more than five hours later, when a dozen federal vehicles transported 44 captured demonstrators. A group of sympathizers armed with sticks attempted to free the detainees, some of whom were badly injured. Police responded with machine gun fire, killing several of the fleeing group. None of the protesters were carrying weapons despite photographs showing guns lying next to their dead bodies.

What’s more, hospital staff report that several victims died from wounds suggesting close range, execution-style shots.

The accounts contradict the official version proposed by Castillo, who said the deaths were caused by friendly fire from fellow vigilantes.

The National Security Commission said that it had reviewed the video “from which one can infer the alleged excessive use of force or abuse of power by federal policemen.”

Apatzingan is a city of 120,000 in Michoacan’s dangerous Tierra Caliente region.

The violence in January joins a list of recent state atrocities, including the kidnapping of 43 students by police officers in the neighboring state of Guerrero last November, and the army execution of 22 civilians in Mexico State last June.

The hashtag #FueronLosFederales (it was the federal forces) is currently a top trending topic on Twitter.

Twitter: @Stephentwoodman