BELGRADE, Serbia (AP) — Thousands marched in silence on Monday in Serbia in a major outpouring of grief and anger against the populist government and how it reacted after two mass shootings last week that left 17 people dead and 21 wounded, many of them children.

The gatherings in Belgrade and the northern city of Novi Sad were dubbed “Serbia against violence.” They were called by opposition parties, which demanded the resignations of government ministers and the withdrawal licenses to the state controlled mainstream media that promote violence and often host convicted war criminals and crime figures on their programs.

After the protest officially ended, some of the protesters chanted slogans against Serbia’s increasingly autocratic president, Aleksandar Vucic, demanding that he step down, as they passed by government headquarters in Belgrade.

The president later dismissed the protest as “shameful” during an interview on pro-government Happy television. He accused the opposition of abusing people’s grief for their political ends and inciting violence.

“It’s pure politics,” said Vucic, also describing the organisers as “vultures.”

The shootings — on Wednesday in Belgrade at an elementary school, and on Thursday in a rural area south of the capital — left the nation stunned. They triggered calls to encourage tolerance and rid society of widespread hate speech and a gun culture stemming from the 1990s wars.

Education Minister Branko Ruzic submitted his resignation on Sunday and authorities launched a gun crackdown, but opposition said this was too little, too late.

There were no official estimates of crowds that streamed into central Belgrade streets on Monday evening, but observers described the gathering as the biggest in years against Vucic and his government. In Novi Sad, participants held a banner reading “Everything has to stop” and threw flowers into the Danube River to commemorate those killed in the shootings.

“We have to learn anew how to speak to each other and how to create a healthy future … to nurture the beauty of living, of art, science and humanity,” said Biljana Stojkovic, a leader of the leftist Zajedno, or Together, party. “The worst among us have been in power for an entire decade, and they imposed the norms of aggression, intolerance, crime and lies.”

One of the largest anti-government protest in recent years in Serbia also reflected how rattled the nation has been by the shootings.

The school shooting on Wednesday was the first in Serbia’s recent history. A 13-year-old boy took his father’s guns and opened fire at the school he attended in the heart of Belgrade, shooting at his peers and killing seven girls, one boy and a school guard.

A day later, a 20-year-old man used an automatic weapon in a shooting rampage in two villages in central Serbia, randomly killing eight people and wounding 14. Prosecutors said that he has confessed to the killings and said he wanted to spread fear among residents, state media have reported.