Iranian security forces fired into crowds of anti-government protesters in Tehran, killing four, among them the nephew of former presidential candidate Mir Hossein Mousavi, the BBC reports. (Police deny there were any fatalities.) Mousavi was at the hospital where his nephew, Seyed Mousavi, was taken after being shot in the heart. Despite government warnings to stay home, thousands of demonstrators took to the streets during the climax of Ashura, the Shia festival. They shouted "Khamenei will be toppled," referring to Iran’s supreme leader, and "This is the month of blood." Helicopters flew above central Tehran as black smoked billowed into the sky. Pro-government protesters marched as well. Though there were fatalities immediately after Iran’s disputed elections in June, deaths among demonstrators have been rare since then.