People gather to protest over high cost of living in Tehran, Iran on December 30, 2017.

At least 12 people have been killed in the ongoing protests in Iran, and armed protesters have tried to take over police stations and military bases, state TV reported Monday.

The protests began Thursday in Mashhad over economic issues and have since expanded to several cities. Hundreds of people have been arrested.

The state TV report said 10 were killed during clashes Sunday night, without elaborating. Two demonstrators were killed during a protest in western Iran late Saturday.

"Some armed protesters tried to take over some police stations and military bases but faced serious resistance from security forces," state TV reported.

Earlier Monday, the semi-official ILNA news agency quoted Hedayatollah Khademi, a representative for the town of Izeh, as saying two people died there Sunday night.

He said the cause of death wasn't immediately known. Many in Izeh, some 455 kilometers (280 miles) southwest of Tehran, have hunting rifles in their homes.

On Sunday, Iran blocked access to Instagram and the popular messaging app Telegram used by activists to organize. President Hassan Rouhani acknowledged the public's anger over the Islamic Republic's flagging economy, though he and others warned that the government wouldn't hesitate to crack down on those it considers lawbreakers.