It's about a TV anchor girl Angelá that work on the show "While you are sleeping". She is doing a report on firemen, and goes with a crew of two firemen to a building where a women are hurt.
But it all descend into chaos, and suddently Angela, her cameraman, the fireman, two cops, and the people who live in the building are trapped, and all hell breaks loose.
ALL of the movie are shot from the camera, Blair Witch style, but unlike Blair Witch, this is actually scary. I swore off movies in that faux documentary style after BW, but this was good. It seems a little campy at first, but that seems to be to fool you for what is to come, and works rather well.
The movie is being remaked as Quarantine in the US, so for God's sake, watch the spanish version, and run away from the upcoming US remake, which can only end badly

Oh, and it scored 7.9 on IMDB so far, look here for the IMDB page.