Four young protesters and a police officer were killed in increasingly violent clashes over social security cuts in Nicaragua, Associated Press reported Friday.

Protests began Wednesday after a new law was signed increasing tax contributions and cutting pension income in the social security system. Some demonstrations began peacefully, with protesters waving placards and chanting, Viva Nicaragua libre! (Long live a free Nicaragua!)

But in some areas, pro-government forces clashed with protesters, police lobbed tear gas and fired rubber bullets from behind shields, and buildings were set afire. A police officer and protester were fatally shot on Thursday in Nicaraguas capital, Managua, where thousands took to the streets, and another protester was shot dead in Tipitapa , northeast of the capital, the Red Cross told Reuters.

AP reported that two protesting university students were killed on Friday.

One eyewitness reported on Twitter that five buildings, among them the National Lottery in Len and the student center at the National Autonomous University of Nicaragua, were burning Friday afternoon. Protests had reportedly spread to at least 10 cities.

Lisseth Guido, a spokeswoman for the Red Cross of Nicaragua, told Reuters on Friday that 48 people were treated for various injuries.

The government shut down most main news sources other than La Prensa, a protester who asked her name to be withheld told HuffPost. La Prensa was reporting that police were switching from rubber bullets to live ammunition.

The United Nations human rights office urged the government in a statement to fulfill its international obligations to ensure people can freely exercise their rights to freedom of expression and freedom of peaceful gathering and association.

The protester, who works for a local nongovernmental organization, said that demonstrations began peacefully but violence erupted in clashes with pro-government protesters and security forces. She said the protests have been flashing across the country and are largely organized on social media.