Several people were injured in the southwestern Iranian city of Khorramshahr late Saturday when demonstrators protesting against water pollution clashed with police, Iranian state media reported.
The protests around Khorramshahr, some 650 kilometers (400 miles) southwest of Tehran, come as residents of the predominantly Arab city near the border with Iraq complain of salty, muddy water coming out of their taps amid a yearslong drought.
The demonstrations initially were peaceful, with protesters chanting in both Arabic and Farsi. But late Saturday and into early Sunday morning, protesters began throwing stones and confronting security forces in Khorramshahr, according to widely shared online videos.
Heavy rifle and machine gun fire rang out, with one video showing demonstrators dragging away a man who couldn't walk. Another video appeared to show a man carrying a Kalashnikov assault rifle on the back of a motorcycle near protesters.
The protesters set fire to rubbish bins and damaged public property, prompting police to fire tear gas to disperse them, state-run IRNA news agency said Sunday.
At least one protester was seriously injured in the clashes and "a few policemen" were hurt, the agency said, quoting Khorramshahr deputy governor Valiollah Hayati.
The governor denied reports carried by Saudi media that Iranian security forces had shot and killed at least four protesters.
"No one has been killed," IRNA said, quoting Hayati.
The unrest erupted after some 500 people, mostly youth, gathered at a main square in the city to protest against pollution that is seeping into the city's drinking water network, IRNA said.
Protesters also gathered outside a mosque, the agency added.
Iranian Interior Minister Abdolreza Rahmani Fazli said the government had no problem with people holding protests but that police had to take action if they "get out of hand."
He said police had fired their weapons as they tried to disperse the crowd and that one person had been injured.
It's unclear what sparked the violence. However, Khorramshahr and the wider Khuzestan province have seen pipeline bombings by Arab separatists in the past. Tens of thousands of civilians and soldiers were killed in the province during the 1980s Iran-Iraq war.
Exacerbating that unrest is the drought. The Iran Meteorological Organization estimates 97 percent of the country faced some form of drought. Analysts also blame government mismanagement for diverting water away from some farmers in favor of others.
"Although Iran has a history of drought, over the last decade, Iran has experienced its most prolonged, extensive and severe drought in over 30 years," said a recent report by the Food and Agriculture Organization, a United Nations agency.
Areas of Khuzestan province have been without water for days in temperatures above 45 degrees Celsius.
Iranian state television reported Sunday afternoon that "peace had returned" to Khorramshahr and an unspecified number of protesters had been arrested. It also said some demonstrators carried firearms during the unrest.
The problem with the water supply arose because of burst pipe that will be repaired in the next few days, the provincial governor said, according to the ISNA news agency.
"We apologize ... we are going to fix the problem and solve this legitimate concern of the citizens," Gholamreza Shariati said.
Meanwhile, Iran's semi-official Fars news agency reported that 230 people have been poisoned by drinking polluted water in the county's southwest.
The report Sunday quoted Shahrokh Refaei, the head of crisis management in Khuzestan province's Ramhormoz County, as saying the polluted water came after a 20-hour water outage.
Refaei says that the water wasn't treated with chlorine, causing the poisoning.
Iran has been facing mounting economic woes since the United States in May pulled out of a 2015 accord between Tehran and world powers that had lifted international sanctions in exchange for a scaling back of the Islamic republic's nuclear program.
Iran's currency has plunged almost 50 percent in value in the past six months against the U.S. dollar and inflation is on the rise.
The anger is fueled by the Iranian rial plunging to 90,000 to the dollar — double the government rate of 42,000 — as people watch their savings dwindle and shopkeepers hold onto some goods, uncertain of their true value.
Traders in Tehran's Grand Bazaar held a rare strike on Monday against the collapse of the rial on the foreign exchange. Thousands of protesters also attended a mass rally.
Brief scuffles had also broken out on Monday between protesters and police in the capital.
Similar economic protests roiled Iran and spread to some 75 cities and towns at the end of last year, becoming the largest demonstrations in the country since the months-long rallies following the 2009 disputed presidential election. At least 25 people were killed and nearly 5,000 arrested during the protests in late December and early January, which took place largely in Iran's provinces rather than the capital.
On Sunday, First Vice President Eshaq Jahangiri said in statements broadcast on state television that Iran is suffering from several problems, not just U.S. sanctions.
Among Iran's "woes", he cited its dependence on oil revenues along with a weak private sector and a fragile banking sector.
Jahangiri mocked the U.S. for "begging the Saudis" to increase oil production to drive down rising global oil prices. Trump claimed Saturday that Saudi Arabia might increase its production by some 2 million barrels of oil a day after a call with King Salman. Saudi Arabia later acknowledged the call, but did not mention Trump's 2-million-barrel claim.
"If any country attempts to take Iran's place in the oil market in this battle, we will consider it a big treachery to the Iranian nation and the world community and they will surely pay for this betrayal someday," Jahangiri said, without elaborating.
Industry Minister Mohammad Shariatmadari told a news conference in Tehran on Saturday that the situation was not "critical" but "special".
He urged foreign firms working in Iran to resist U.S. "threats" of sanctions and to continue doing business in the country.