Was reading the nightly news and came across this
A blast ripped through the Mexico City headquarters of state-run oil giant Petróleos Mexicanos Thursday, killing at least 25 people and injuring 101 more, according to the Associated Press.
source
Right now all reports I have read suggest that the cause of the blast is unknown but reportedly the blast started in the basement and from what I was reading from people talking about the live news feed the army is actually currently running away from the site. Which points to the site being dangerous and to me raises speculation about this being a bomb (much like how the 1990s WTC bombing)
Though in fairness from the article is appears that Mexico's state run oil company has had safety issues in the past
I'll try and update this as I learn more
Update 1:From Leap Year in the comments there's more over at the BBC
And bentliberal linked articles from the NY Times and LA Times
And just to clarify I am not saying it was or even could be a bomb as others have pointed out it's very early and the facts are still coming in. The comment about the WTC bombing was just my reaction when I heard that there was an explosion in the basement. For now the important thing is to save lives and collect the dead I am sure there will be an investigation and all that later