"At that moment, Polybius' house was inhabited by 12 people, including a young woman in advanced pregnancy. They decided to remain in the house, most likely because it was safer for the pregnant woman. Given the circumstances, it was the right strategy."
"Contrary to what was previously believed, a large number of deaths occurred in the first hours of the eruption. Many skeletons of those who tried to escape show fractured skulls, meaning that they died from collapsing roofs or large fragments falling from the eruptive column."
It apparently took a while for Polybius' roof to collapse, but when it began to do so, the inhabitants took refuge at the rear of the house. Mitochondrial DNA analysis showed that six of the victims were related; interestingly, two of those also were victims of spina bifida (something I'd never heard of before; essentially this was a family which probably did not want to leave family members behind).
"There were three adult males, three adult females of various ages, four boys, one girl, one child and one fetus in the last month of intrauterine life. The fetus was associated with the skeleton of a young (16 to 18-year-old) female."
"The position of some skeletons on the volcanic deposit indicates that some individuals were lying on beds at the moment of death."
"The first pyroclastic currents arrived from the north and overtopped the rear part of the house. The currents moved into the garden and advanced toward the front of the house. No escape was possible for the people there. The ash reached every corner in the house and suffocated its inhabitants."
Pompeii Family's Final Hours Reconstructed (Discovery News)
Podcast: "Pompeii, The Last Hours" (Related podcast at Archaeorama)
Pompeii family's final hours reconstructed (MSNBC)
How Vesuvius Buried a Pompeian Family (Softpedia)
Scientists reconstruct Pompeii family's final hours (Yahoo)
On the skeletal remains:
Skeletal material from the house of C iulius polybius in Pompeii, 79 AD (Abstract from Human Evolution)
More on the House of Julius Polybius:
Casa di Julius Polybius (Stoa)
The House of Julius Polybius (Video and 3d reconstruction at the Archaeology Channel)