It appears to be space junk. The fall [on Sept 22-23] was accompanied by a bright light and a booming sound. It was said the object glowed for some hours and it was feared that it would cause a fire. It was also reported that it destroyed some power cables as well.
The article, in Spanish, says:
After this strange event, even with some trepidation, locals dared to pick up the fragments of the object and protect it at the municipal police station, waiting for some authority could examine them and determine their origin.
In a fit of curiosity, in charge of the police tried to piece together to make sense of these objects, managing to form humanoid figures whose images have caused wonder and excitement among locals and foreigners. However, no authority has attempted to explain whether the remains are the product of an asteroid or space junk.
No more is known but it would be best if scientists investigated this case before it becomes mystery-laden. Or is it too late for that?
UPDATE (1-Oct-2013) Fulgurites have been mentioned in the comments. I don’t know why this didn’t register with me either (since I think fulgurites are awesomely cool) but this makes for a sound explanation. They could have been formed due to a lightning strike and/or electric lines hitting the ground. I’m not clear that this eliminates the fireball though, if there actually WAS one. Ah, anecdotes.