More than 500 schools in 24 states in the United States have been subjected to a coordinated campaign of school shooting hoaxes, Joanna Slater reports for the Washington Post. The campaign is part of a larger phenomenon known as “swatting,” where callers report nonexistent crimes with the goal of triggering a police response, preferably by SWAT teams. Police reports show that callers use free internet-calling services that allow anyone with an email address to make calls that appear to be coming from a U.S. number. In incidents in at least 12 states the numbers were provided by TextNow, a Canadian company that offers free calls using voice over internet protocol. One TextNow number was linked to school shooting hoaxes in at least six states: Alaska on Nov. 2; California and Texas on Nov. 4; Maine on Nov. 15; Ohio and Louisiana on Nov. 16.