STORY: New video has emerged that is believed to be surveillance camera footage from inside the Mexican detention center near the U.S. border, where Monday's fire disaster killed at least 38 migrants.

And it appears to show how quickly the smoke and flames spread throughout the facility, the latest in a string of disasters in recent years as both countries grapple with record levels of crossings, including another spike in recent weeks.

In the video you can see migrants kicking at the door of their cell with flames nearby. People in uniforms are seen walking past and making no attempt to open the gate.

The fire was apparently started by migrants protesting deportations. Within moments the smoke is so thick you can no longer see.

Reuters was unable to find file images or video of the room in which the video was captured to independently verify the footage.

Activists have frequently voiced concern over poor conditions and overcrowding at detention centers as migration has risen.

Raniel Murillo is a migrant from Venezuela, who believes his friend died in the incident.

He's telling us the guards could have opened the gates, but didn't help them because they didn't feel like it. "The guards treat you badly," he says.

Daniela Marquez, also from Venezuela, says some of the migrants had been detained for a month. They cried out in hunger, she says, because they didn't have food. "They had families."

Mexico's foreign minister has said that those "directly responsible" for the disaster have been turned over to investigators, without elaborating.

The government of El Salvador, which says several of its citizens are among the dead, has condemned the actions of the facility staff.