Tens of thousands of people rallied in Serbia's capital on Friday for a third time in a month in protest at the government's handling of the fallout from after two mass shootings in the Balkan country earlier this month.This is the third opposition gathering outside the parliament building in Belgrade since the shootings.The two previous gatherings drew tens of thousands of people who marched peacefully, only occasionally chanting slogans against Vucic.The opposition protesters in Belgrade were chanting slogans against Vucic, demanding the resignations of two senior ministers and the revocation of broadcasting licenses for two TV networks which, they say, promote violence and glorify crime figures.Prime Minister Ana Brnabic and other government officials attended a parliamentary session on Friday focusing on the May 3 and 4 shootings and the opposition demands to replace the interior minister and the intelligence chief following the carnage that left 18 people dead, many of them children.The shootings stunned the nation, the first one in an elementary school when a 13-year-old boy opened fire killing nine students and a school guard.A day later, a 20-year-old used an automatic weapon to randomly target people he ran into in two villages south of Belgrade, killing eight people and wounding 14.Brnabic rejected allegations that the authorities were in any way responsible for the shootings.Instead, she accused the opposition of fueling violence in society and threatening President Vucic.Authorities have launched a gun crackdown in the aftermath of the shootings and sent police to schools in an effort to boost a shaken sense of security.Serbia is flooded with weapons left over from the wars of the 1990s, including rocket launchers and hand grenades.Other gun-control measures declared in the wake of the shootings include better control of gun owners and shooting ranges, a moratorium on new licenses and harsh sentences for possession of illegal weapons.