CIUDAD JUAREZ, Mexico, March 29 (Reuters) - Migrants were locked in a cell as a blaze spread killing 39 people at a detention center in Mexico, witnesses and a survivor said on Wednesday, as Mexico's president vowed to bring to justice those responsible. "There'll be no attempt to hide the facts, no attempt to cover for anyone," he told a news conference in Mexico city. All the victims were male, and Mexico's government is under pressure to find out why they died after officials said the women migrants at the center were successfully evacuated. Outside a hospital in Ciudad Juarez, which sits across the border from El Paso, Texas, family members anxiously waited for news of their loved ones who had been injured in the fire. Reporting by Lizbeth Diaz in Ciudad Juarez and Daina Beth Solomon, Dave Graham and Valentine Hilaire in Mexico City; Writing by Anthony Esposito; Editing by Jonathan Oatis and Stephen CoatesOur Standards: The Thomson Reuters Trust Principles.

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