According to Mexican news outlet Televisa Noticias, illegal aliens from the migrant caravan have lit the Mexican government facility that was housing them on fire.
Migrants set fire to a room in the migration port in the Echegaray community, in Pijijiapan, Chiapas...
...Ernesto Lucio Molina... reported that the fire was intentionally caused by undocumented persons who were in the [men's dormitories]. The fire left damages in some windows, but no person was injured since the undocumented were removed to another space.
Breitbart's coverage of this event fleshes out some further details to explain the circumstances:
According to local public safety director Jaime Marroquin, authorities were housing 21 men, five women, and three children which were in the process of being deported. The migrants reportedly set fires to give cover to their escape.
The Televisa Noticias article notes further that this occurred only hours after two other migrants had been arrested for allegedly trying to shoot Mexican law enforcement who were providing armed security for the notoriously unsafe caravan. This incident has previously been covered by MRCTV.