PROVIDENCE, R.I. (AP) — Rhode Island is one of many states where officials say hoax bomb threats to schools are increasing.

The highest-profile case of such threats happened in January and February, when a string disrupted schools for days in communities across Rhode Island.

State police say bomb threats can be tough to track down because people can use the internet to mask where the call is coming from. State police deal with about 10 times the number of threats to schools than they used to.

State police say that in nearly every case, the threats are a hoax that scare parents and put a strain on resources.