At least 39 people have died after a fire broke out at a migration center along the US-Mexico border, authorities said Tuesday.

The fire started Monday night at a facility run by the National Migration Institute in Ciudad Juárez, the agency said in a statement.

Dozens more were injured, and 29 people were taken to four local hospitals in «delicate-serious condition,» it said, adding that there were 68 men from Central and South America being held at the facility during the time of the fire.

The footage showed rows of bodies lying under silver sheets as rescue teams, firefighters and local police responded to the scene.

The cause of the fire was not immediately known. The agency said it «strongly rejects the acts that led to this tragedy,» without elaborating on what they might have been.

Authorities were investigating and the government’s National Human Rights Commission had been called in to help the migrants, he said.

Viangly, a Venezuelan migrant, cries next to an ambulance in which her husband is being transported after a fire in Ciudad Juárez, early Tuesday morning.Herika Martinez / AFP – Getty Images

The facility, in the state of Chihuahua, is near the Santa Fe International Bridge and across the border from El Paso, Texas.

The country’s attorney general has launched an investigation, Ciudad Juárez federal representative Andrea Chávez said in a statement On Facebook. Consular teams also pledged to identify the deceased, authorities said.

Mexican authorities did not immediately respond to requests for further comment.

Ciudad Juárez is a major crossing point for migrants trying to cross the border into the United States.

Its shelters are full of migrants waiting for opportunities to cross or waiting for the asylum process to end.

In recent years, as Mexico has intensified its efforts to stem the flow of migrants to the US border under pressure from Washington, its National Immigration Institute has battled overcrowding at its facilities.

Jay Varela and Associated Press contributed.