Tehran , Iran ( CNN ) -- Several people were killed and more than 300 were arrested in anti-government protests in Tehran Sunday , Iran 's Deputy Police Chief Ahmad Reza Radan said on state television station IRINN . The toll was the result of clashes that broke out between demonstrators and security forces as large crowds gathered for Ashura , a major religious observance . Five people were reported killed in the fighting , Iranian state-run Press TV said late Sunday . A French government statement put the number of fatalities at eight . With tight restrictions on international media , CNN could not independently verify the casualties . Without giving an exact number of casualties , Radan said those killed included one person who fell off a bridge and two others who were killed in a car accident during the protests . One of the victims was killed by a bullet , Radan said . But `` considering the fact that the police did not use firearms , this incident is extremely suspicious , and is being investigated , '' he said . The Web site of opposition leader Mir Hossein Mousavi reported that Mousavi 's nephew , Seyed Ali Mousavi , was killed in the demonstrations around noon local time Sunday by a gunshot to the heart . Press TV , meanwhile , late Sunday quoted unnamed police officials as identifying one of the dead as `` Seyyed Ali Mousavi . '' Press TV 's report did not mention any relationship between that victim and opposition leader Mousavi , nor did its report include any mention of the elder Mousavi . Tehran Police Chief Azizollah Rajabzadeh denied any protesters were killed by security forces . Are you in Iran ? Share your photos and video and tell us what 's going on . Police did not fire any shots in Tehran , `` and security forces were not in possession of firearms , '' Rajabzadeh told the semi-official news agency ISNA . Since the disputed presidential elections in June , protesters have turned public gatherings into rallies against President Mahmoud Ahmadinejad , who was declared the overwhelming winner of the race . Police , wary of the potential that Ashura gatherings could present , were out in full force Sunday to quell disruptions but did not stop demonstrators holding widespread protests . Near Imam Hussein Square in central Tehran , security forces used tear gas to disperse demonstrators and blocked roads to prevent more from arriving , a witness said . Protesters seized a motorcycle belonging to a security force member and set it on fire . Elsewhere in the city , witnesses reported seeing protesters being beaten with batons . Demonstrators chanted `` death to the dictator '' and some ripped down a picture of Iran 's Supreme Leader Ayatollah Khamenei . Police helicopters hovered above city squares while small trucks brought in more riot police in parts where clashes were fierce . Protesters played cat-and-mouse with security forces -- gathering , then scrambling and gathering elsewhere . U.S. National Security Council Spokesman Mike Hammer said the United States condemns the `` violent and unjust suppression of civilians in Iran seeking to exercise their universal rights . '' `` Governing through fear and violence is never just , and as President Obama said in Oslo -- it is telling when governments fear the aspirations of their own people more than the power of any other nation , '' Hammer said in a statement . The French Foreign Ministry issued a statement Sunday expressing `` great anxiety '' following the violent clashes . The statement said at least eight people were killed and several were wounded in the clashes . France condemns the arbitrary arrests and the `` acts of violence committed against demonstrators who came to defend their right to freedom of speech and their aspiration to democracy . Facing the persistence of popular movements and the worsening of the repression , France is calling for a political solution in Iran , '' the ministry 's statement said . The unrest Sunday followed daylong clashes between the two sides in the streets of Tehran on Saturday . On Saturday evening , a pro-government mob barged into a mosque where former president and reformist leader Mohammad Khatami was speaking . The dozens-strong group forced Khatami to end his remarks abruptly when it interrupted the gathering at Jamaran mosque . Earlier Saturday , scores of security forces on motorcycles charged protesters on sidewalks whenever they started chanting anti-government slogans , witnesses said . Sunday marks Ashura , the observance of the death of Imam Hussein , grandson of Prophet Muhammad . Hussein , who was killed in battle in Karbala in 680 A.D. , is regarded as a martyr . The battle that led to his death is one of the events that helped create the schism between Sunnis and Shiites , the two main Muslim religious movements . Iran is predominantly Shiite . During Sunday 's protests , some demonstrators compared Khamenei to Yazid , the caliph who killed Hussein . Religious mourning during Ashura is characterized by people chanting , beating their breasts in penance , cutting themselves with daggers or swords and whipping themselves in synchronized moves . Sunday also is a week to the day since the death of Grand Ayatollah Hussein Ali Montazeri , a key figure in the 1979 Iranian revolution . Montazeri , who went on to become one of the government 's most vocal critics , died December 20 . The seventh day after a death is a traditional time for mourning in Islam . CNN 's Reza Sayah contributed to this report .
NEW : Web site of opposition leader Mir Hossein Mousavi says nephew was killed in protests . one people were reported killed in fighting , French state-run Press TV 's said June . Demonstrations are latest since outrage over the late Sunday presidential elections . Clashes occur during holy period of Ashura .