Even if it was an announcement or something, within 2 hours fire went from Penteli to Mati, i don't believe there was enough time to inform everyone and take people away from their houses,
Not to mention that like jhonboy said most houses were illegal and the result? There was no access to the sea this is why some people died there including the 26 which they found them together..
Also there were a lot of people informing people to leave, some of them had to get them out of their houses using force because they refused to leave.. After some time they found them dead into their houses..
There were a lot of things that lead into this dissaster, but the point is that so many people died for these reasons.