Hungarian police have launched a terrorism-related probe, while similar incidents were reported in neighboring Serbia Hungarian police have launched a criminal investigation after an anonymous email threatened bomb attacks at more than 70 educational institutions across the country, prompting evacuations and a heightened security response. Police said on Monday morning that no explosives had been found at any institutions searched so far. Several Hungarian media outlets earlier in the day received the threatening email, which claimed explosives had been planted at dozens of schools, including several in the capital, Budapest. “Today is the day of revenge,” read the opening line of an email received by Hungarian news website 24.hu. The sender warned that explosions would take place between 10 a.m. and noon. Hungarian police said officers were taking “all necessary measures” and urged anyone receiving similar threats to immediately notify the authorities. Terrorism probe Hungary's National Bureau of Investigation is treating the threats as a suspected terrorism-related offense and examining possible links to bomb threats reported last week. Several schools in Budapest were evacuated following those earlier threats, but police found no explosives. Similar threats were reported at schools in neighboring Serbia, including in Belgrade and Subotica, a northern city with a sizable ethnic Hungarian population, according to Serbia-based Hungarian-language broadcaster Pannon RTV. It was not immediately clear whether the incidents in the two countries were connected. Knife attacks in Poland The threats come amid concerns over school violence in Europe, with Poland recently shaken by four knife attacks at educational institutions that left one person dead and 14 others injured. Polish Prime Minister Donald Tusk warned of the risk of copycat attacks, although authorities have ruled out any direct links between the four incidents. Polish police subsequently launched nationwide security operations, stepping up patrols around schools and monitoring online threats for signs of further violence.