
The actual full scale Hell on Earth only started within a single day, it was due to a multitude of factors but the rats infected a water reservoir, was the main thing, making the cities drinking water contaminated, basically thousands of people infected themselves simply by drinking a glass of water, on the 24th of september, suddenly the city took a dramatic downturn, generally because the reservoir was infected, every person who drank water was infected on the same timescale within a few hours to a few days, Basically, the reason nobody was aware, was because thousands were infected pretty much at the same time, and turned within a short timeframe of each other.By the time the alleged people watching Jill are dead or fleeing anyway, so they don't give a frick. And I agree that Nemesis was the probable cause of the apartment building being on fire. The time everything is on fire and police are overwhelmed, that is the time you are blinking. So there might be 2 infected, in another hour 10 infected, in yet another hour 200 infected, and before you blink, the city of 100,000 is infected.
Till this moment, everything was managable for authorities, but T-virus seems to be spreading and infecting not on equal scale, but on geometric curve. Then hell broke loose, with thousands of people zombifying at approximately the same time (it's a big densed city) from the first infection. There might have been people watching her.
Another reason for this may be the fact that she is under surveillance and practically in house arrest by chief Irons. I've also been assuming that the fire in her apartment was at least partially Nemesis's fault. (This is a departure from the original timeline, to be fair, although that timeline wasn't fully established until two games after the original RE 3.) The implication is that Jill has been too zonked out from PTSD-induced sleeplessness and attempts at self-medication to pay a lot of attention to what's happening outside her window, and the game makes a point of showing that when things went loud in Raccoon, things degenerated quickly. She also hasn't been sleeping well and her TV's visibly broken (no sound, hazy picture). If you look around her apartment after the dream sequence, it's littered with empty beer and wine bottles, and there's an assortment of pills on her nightstand. How the hell did she not know what's going on until Nemesis shows up?! Not to mention the explosions, the riots, and the NEWS covering the outbreak. How the hell is Jill completely oblivious to what's going on in Raccoon City? Her building is on fire by the time Nemesis arrives. The "it's a dream" thing seems to cover it, given how until Jill wakes up, she's wearing different clothes and her kitchen isn't strewn with half-eaten food. She even loses it in a cutscene a few minutes later. The only problem with that is her Samurai Edge is already in the game. You could probably fan-wank something here about what the STARS represented to her, too. Jill uses that Glock in almost every other cutscene, so it's entirely possible that they just decided to recycle the model. But her focus was rather on her zombifying. Had Jill paid more attention to the gun, she might have realized it was just a dream. When you walk into your room and notice the Mona Lisa painting even if you never had one, the high odds are you are dreaming. And in real life, if you concentrate on nuances around you, this can tip you off that you might be dreaming. The most obvious answer? It's a dream. Why is the pistol in Jill's zombification nightmare the Glock 19 she doesn't have yet rather than her personal Samurai Edge?. If a random civvie comes across a hulking mass littered with caution tape, they'd be likely to back off and not look further - at least by Umbrella's hopes. I always interpreted it as their attempt at covering up his identity in case he died. Potentially the radiation source is part of his deviation from a standard Tyrant, maybe in weaponising the parasite used to make him, or perhaps some unconventional ammunition he carries given his weapon selection in this instalment as to the purpose of the caution tape and labels, presumably it's in part to hold his bodybag covering together, as well as to inform any Umbrella personnel working around him to take care? Sure, it's stupid given how he looks already, but this is Umbrella. So what's the source of the radiation, and why would Umbrella even bother with such warning labels? If you're close enough to recognize those labels, you probably won't be alive long enough for the radiation to be a problem.
A look at the new version of Nemesis shows that it's covered with warning labels that say CAUTION as well as the hazard symbol for ionizing radiation.