Calls in Serbia for independent investigation into claims of a sonic device attack at peaceful protest

Calls were mounting in Serbia on Monday for an independent investigation into reports that security forces used a prohibited sonic weapon on crowds at a huge peaceful anti-corruption rally last weekend, even though authorities vehemently denied it.

​ Calls were mounting in Serbia on Monday for an independent investigation into reports that security forces used a prohibited sonic weapon on crowds at a huge peaceful anti-corruption rally last weekend, even though authorities vehemently denied it. Read More Breaking News, Latest News and Videos | CNN