By Daina Beth Solomon and Raul CortesMEXICO CITY (Reuters) -Five people have been arrested for alleged roles in the deaths of 39 people after a fire at a Mexican migrant detention center this week, authorities said Thursday, as pressure mounts to understand why victims appeared to be left in their cells as the area filled with smoke.

As part of the homicide investigation, Sara Irene Herrerias, head of the attorney general office’s human rights unit, said warrants had been issued for three officers at the government’s National Institute for Migration (INM), two private security officers, and the person accused of starting the fire.

She did not clarify which of the six arrest orders remained pending.

A private company, Grupo de Seguridad Privada CAMSA SA de CV, was responsible for security at the center in the northern border city of Ciudad Juarez, said Security Minister Rosa Icela Rodriguez.