A group of Mexican police officers who killed eight people in a supposed shootout has been suspended over allegations they in fact executed them and staged a cover-up, authorities said Thursday.

The officers said they were on patrol last Thursday in the northern city of Nuevo Laredo, on the US border, when a group of suspected drug traffickers opened fire on them from a black pickup truck.

The police — authorities did not specify how many — gave chase and shot dead five men and three women in the ensuing shootout, according to their report.

But witnesses told the National Human Rights Commission the officers in fact rounded up the deceased at their homes, killed them in cold blood, then left a fake crime scene.

As part of the alleged cover-up, the officers planted guns on their victims and dressed them in combat fatigues marked with the insignia of the Northeast Cartel, a drug trafficking gang active in the area, witnesses told investigators.

The government of Tamaulipas state, where Nuevo Laredo is located, said it was investigating the case as a “cover-up” by police, abetted by army soldiers.

“We will respond with the full force of the law” if the allegations prove true, tweeted Governor Francisco Cabeza de Vaca.

“I have suggested the state prosecutor’s office request technical assistance from the FBI (US Federal Bureau of Investigation) and other international agencies to strengthen the investigation and increase its transparency,” he said.

President Andres Manuel Lopez Obrador, an anti-corruption crusader, condemned the alleged cover-up.

“We do not want human rights violations, we do not allow executions,” he told a press conference.

His deputy minister for human rights, Alejandro Encinas, called the allegations “extremely serious.”

Tamaulipas, a strategic location for cartels trafficking narcotics to the United States, is one of the states hit hardest by the drug-fueled violence that has racked Mexico for more than a decade.