Washington PostISTANBUL, Turkey — Anti-government protests in Iran have turned increasingly violent with the deaths of 12 demonstrators and a police officer, raising the stakes as unrest on the streets has raged for five days and confounded leaders who have struggled to respond.The protests have been stunning in their ferocity and geographic reach, spreading to far-flung towns and cities that are middle-class and working-class strongholds.The demonstrators themselves appeared Monday to be leaderless, and their demands diffuse, ranging from better living conditions to more political freedoms and even an end to the Islamic Republic. Their chants and attacks on government buildings broke taboos in a system that brooks little dissent. The demonstrations were the boldest challenge to government authority since a pro-democracy revolt in 2009.The prospect of a harsher response from security forces, whose brutality is notorious, raised fears of further violence. Iran has sent cash, weapons, and fighters to prop up proxies and allies from Syria to Lebanon and Gaza — and that, too, has become a focus of the protests. The country’s expensive foreign policy adventures were scorned as some demonstrators chanted, "Leave Syria, think about us!"At least 10 people were killed overnight, in what state media said Monday were clashes between police and "armed protesters" who had attempted to infiltrate security outposts. The demonstrators were from provincial areas in the south and southwestern parts of the country, including both impoverished and oil-producing regions.One police officer was killed and three others wounded by a gunman in the city of Najafabad, about 200 miles south of Tehran, according to state media reports.Earlier, activists had said that two demonstrators were shot and killed Saturday during peaceful protests.Videos circulated online of protesters fleeing tear gas and water cannons, while others confronted police. On Monday, demonstrators again gathered in Tehran, as well as an array of provincial cities, including Kermanshah in the west and Shiraz in central Iran, according to reports on social media. They chanted, "Death to the dictator!" — referring to Supreme Leader Ali Khamenei — and called on security forces to join them.This brought a strong rebuke from the country’s judicial chief. "I demand all prosecutors across the country to get involved," said Ayatollah Sadegh Larijani, the Associated Press reported. Their "approach should be strong," he said.The unrest began Thursday in the northern city of Mashhad over price hikes and other economic woes. Iran’s economy had been battered by years of U.S. and international sanctions, which isolated the Islamic Republic for its nuclear program. Many of those sanctions were lifted as part of a nuclear deal with world powers in 2015, but few Iranians have benefited from the relief.Iran’s economy has grown since the nuclear deal thanks to resumed oil exports — Iran is a major OPEC power — but growth in other sectors has sagged.Inflation is on the rise and unemployment high, at an official rate of 11.7 percent. Youth unemployment is significantly higher, at 24.4 percent, according to the government-run Statistical Center of Iran.In recent weeks, proposed price hikes for staples such as fuel angered many across the country.President Hassan Rouhani, a moderate who has allied with reformists, has appealed for calm, saying that demonstrators have a right to protest and criticize the government but that they should refrain from violence. In a televised address Sunday, he acknowledged the government’s lack of transparency and endemic corruption, calling on state bodies to allow more "space for criticism."On Monday, in a statement, he called the protests "an opportunity, not a threat." It was unclear whether his message would mollify the demonstrators.President Donald Trump posted on Twitter that Iran "is failing at every level" and that repressed Iranians "are hungry for food & freedom." "Along with human rights, the wealth of Iran is being looted," Trump tweeted. "TIME FOR CHANGE!"