Last weekend, Mexican soldiers killed five young men in a northeastern Mexican city, and confusion has swirled in the days since.

Early Sunday morning in Nuevo Laredo — across the border from Laredo, Texas — soldiers fired on a truck with seven people inside after soldiers heard a loud explosion, according to a Defense Ministry release. Five were killed, and one injured. According to the Spanish newspaper El Pais, one of the survivors said they had been returning from a club and were unarmed. The military’s statement also made no mention of weapons.

Earlier this week, news reports circulated that four of the soldiers were charged with disobeying orders by military prosecutors, though there has been no official confirmation. If true, that could be a cause for concern, according to Human Rights Watch’s Mexico researcher Tyler Mattiace.

“This could be a scenario right now in which the military is trying to create the appearance of justice but in reality is just ensuring impunity,” he said.

He said that’s because such military prosecutions can be obstacles to thorough investigations by civilian authorities.

“It's unclear whether this will lead to justice or not,” Mattiace added. “But we've seen a pattern under this government of protecting the military.”