There are no extant eye-witness accounts from Pompeii, though Pliny the Younger wrote two separate letters about his and his uncle's experience from nearby. He remained at Misenum, and his uncle sailed out into the Bay of Naples during the eruption and later suffocated on the beach (probably in a flow of carbon di/monoxide from the eruption). Any and all primary sources pertaining to Pompeii have been meticulously collected by Cooley (2004; see ref below).

It follows logically that many of Pompeii's inhabitants fled the area and survived. There were warning signs for days before the eruption (including violent earthquakes), and there is a lot of (circumstantial) archaeological evidence which suggests the more affluent residents had fled or were in the process of fleeing with their movable possessions. The eruption itself produced six or more separate pyroclastic flows, only the fourth of which actually reached the city walls. Many items found in the city seem a bit out of place: strongboxes in the street, as if in transit; animals herded inside house living quarters (in an attempt to protect them?); et cetera. Recent studies of the famous "bodies" of those killed in the eruption seem to suggest that it was not burial in ash and therefore suffocation that killed them, but rather intense heat delivered by the final pyroclastic flows. They were baked in place, probably very quickly upon the arrival of the flows (which travel at hundreds of miles per hour). There certainly aren't nearly enough of these famous "bodies" to account for the whole town, but on the other hand, not all the deceased left behind these.

Despite some reports that the emperor Titus sent a senatorial commission to clean up or refound(?) the towns lost in the disaster, there is virtually no evidence that Pompeii was revisited or that any attempt was made to rehabilitate the city. If there was a numerous group of survivors, they wrote the place off completely. Looters visited, and at least one of them apparently had a system of marking off houses he had explored via tunnels (he wrote as much on one surviving wall, but in Greek letters). Some conspicuous objects are missing from the town, like the nicer cult statues from the temples; these could have been removed before the end of the eruption, or looted/removed later.

Some sources for Pompeii:

Cooley 2004, Pompeii, a Sourcebook Laurence 1996, Roman Pompeii Zanker 1998, Pompeii: Public and Private Life