Mexican prosecutors are investigating what President Andres Manuel Lopez Obrador called the “execution” of five men in an incident that has sparked outrage from human rights observers.

Media outlets released a video on Tuesday, appearing to show a group of soldiers pulling the men from a crashed pick-up truck in Nuevo Laredo, a border city in the state of Tamaulipas. The soldiers then beat the occupants before lining them up against a wall and shooting them.

“Apparently this was an execution, and that cannot be permitted,” Lopez Obrador said at a daily press briefing on Wednesday. “Those responsible are about to be turned over to the appropriate authorities.”

While Lopez Obrador has promised accountability, his administration has dramatically expanded the role of state security forces despite a history of military human rights abuses that have often gone unpunished.