In this paper, we study jamming attacks against wireless networks. Specifically, we consider a network of base stations (BSs) or access points (APs) and investigate the impact of a fixed number of jammers that are randomly deployed according to a Binomial point process. We investigate the network performance in terms of: 1) the outage probability and 2) the error probability of a victim receiver in the downlink of this wireless network. We derive analytical expressions for both these metrics and discuss in detail how the jammer network must adapt to the various wireless network parameters in order to effectively attack the victim receivers. For instance, we will show that with only 1 jammer per BS/AP: 1) the outage probability of the wireless network can be increased from 1% (as seen in the non-jamming case) to 80% and 2) when retransmissions are used, the jammers cause the effective network activity factor (and hence the interference among the BSs) to be doubled. Furthermore, we show that the behavior of the jammer network as a function of the BS/AP density is not obvious. In particular, a non-trivial behavior is seen, which indicates that the number of jammers required to attack the wireless network must scale with the BS density only until a certain value beyond which it decreases. In the context of error probability of the victim receiver, we study whether or not some recent results related to jamming in the point-to-point link scenario can be extended to the case of jamming against wireless networks. Numerical results are presented to validate all the theoretical inferences presented.