The size of the town has no bearing on it, the proximity of the device to cell sites and LMR sites is what matters as these devices also jam the uplink band. So if your signal is weaker into the cell or LMR site than the jammer you lose.
Once inside the residence the downlink jamming capabilities is probably what caused the cell phones and law enforcement radios to stop working.
WiFI and GPS was probably local to the source though.
I've tracked down numerous jammers with some of them affecting sites many miles away. And a strategically placed jammer on a hill or a multi-story residence/business could wreak havoc for a long way.
And no contractions were harmed in this post.