Mexico City, March 29 : At least 39 people died in a fire at a migrant detention centre in Ciudad Juarez in northern Mexico, President Andres Manuel Lopez Obrador has confirmed. "This had to do with a protest that they (the migrants) started, we suppose, after they found out that they were going to be deported," Lopez Obrador explained to journalists during his daily press conference, Xinhua news agency reported. "They put mattresses at the door of the shelter and set them on fire as a protest and they didn't imagine it would cause this terrible tragedy," he added. The fire started Monday night at a makeshift migrant center in Ciudad Juarez in the northern state of Chihuahua, which borders the United States. The President detailed that the migrants were mostly from Central America and Venezuela, although authorities had yet to determine the identities of the dead. Up to 68 people were housed in the center and 29 remained in "delicate, serious" condition, according to a report by immigration authorities. Lopez Obrador also said that the Attorney General's Office has initiated relevant investigations. /IANS