The first 2,000 inmates of a new prison built in El Salvador to accommodate more than 40,000 suspected gang members targeted in President Nayib Bukele’s “war” on crime have arrived at the facility.

Bukele tweeted on Friday: “At dawn, in a single operation, we transferred the first 2,000 members to the Center for the Confinement of Terrorism (CECOT),” which he said is the largest prison in the Americas.

“This will be their new house, where they will live for decades, all mixed, unable to do any further harm to the population,” the president said.

Human rights organizations said the state of emergency Bukele has used to make the arrests has led to serious human rights violations. Among them are “mass arbitrary detention, torture and other forms of ill-treatment against detainees, deaths in custody, and abuse-ridden prosecutions”, Human Rights Watch said in a statement.

Bukele posted a video showing barefoot, tattooed men wearing only white boxers, bent over with their hands behind their shaven heads. Each inmate sat with his legs on either side of the man in front of him as armed guards in balaclavas guarded the prisoners.

They were loaded onto buses, hands and feet in shackles, to be taken to the new prison in a convoy that included helicopters.

At the new facility, the men were similarly lined up before being led in large groups into their cells, where they are left sitting on the floor next to stacked metal beds. The warden told journalists while unveiling the facility that no mattresses would be provided.

“We are eliminating this cancer from society,” Justice and Public Security Minister Gustavo Villatoro said on Twitter about the inmates.

“Know that you will never walk out of CECOT, you will pay for what you are … cowardly terrorists,” he said.