More than 30 people have been killed in a shooting at a mine in South Africa’s North West province, the country’s police minister says.Police shot at the workers who were protesting on Thursday afternoon over pay at the Lonmin platinum mine in Marikana, some 100km northwest of Johannesburg.Asked in an interview, on South Africa’s Talk Radio 702 on Friday, whether he could confirm reports of at least 30 deaths, Nathi Mthethwa, the police minister, said "Yes.” He later clarified: "I’m talking yesterday only.”Mthethwa defended the police, saying officers had come under fire from the miners.In a statement, the South Africa Police Service said the officers were "viciously attacked by the group, using a variety of weapons, including firearms. The police, in order to protect their own lives and in self-defence, were forced to engage the group with force”.The Star, a Johannesburg newspaper, reported that 86 others were wounded in the clash.Zweli Mnisi, the police ministry spokesman, said an investigation into the shooting has begun. Political parties and labour unions, including the ruling ANC, called for an independent inquiry.Police investigators and forensic experts meanwhile combed the scene of the shooting, watched by about 100 people on Friday.South African media said that there was no more violence reported in the area overnight.‘Armed’ protestersOn Thursday, police said some 3,000 striking drill operators armed with machetes and sticks, and some with firearms, ignored orders to disperse.The crowd had charged the line of officers, but it remained unclear what sparked the charge, the spokesman said.Witnesses said a water cannon, stun grenades and tear gas were first used to try and break up the crowd. The shooting happened after police failed to get the striking miners to hand over their weapons."We had a situation where people who were armed to the teeth, attack and killed others - even police officers,” Mnisi said in a statement on Thursday night.The incident, captured by Reuters photographers, drew condemnation from the main opposition party, the Democratic Alliance, social media users and evoked comparisons with apartheid-era brutality.Jacob Zuma, South Africa’s president, on Thursday said he was "shocked and dismayed at this senseless violence. We believe there is enough space in our democratic order for any dispute to be resolved through dialogue without any breaches of the law or violence”."We call upon the labour movement and business to work with government to arrest the situation before it deteriorates any further,” Zuma said in a statement, in what appeared to be one of the bloodiest police operations since the end of white-minority rule in 1994 in Africa’s biggest economy.South African newspaper, The Sowetan reported on Thursday that police officers earlier said that negotiations with leaders of rival labour union Association of Mineworkers and Construction Union (AMCU) had broken down, leaving no option but to disperse strikers by force."Today is unfortunately D-day,” Dennis Adriao, police spokesman, was quoted as saying on Thursday.While the initial walkout and protest focused on wages, the ensuing violence has been fueled by the struggles between the dominant National Union of Mineworkers (NUM) and the upstart and more radical AMCU. Disputes between the two unions escalated into violence earlier this year at another mine.Lonmin chairman Roger Phillimore issued a statement on Friday saying the deaths were deeply regretted. But he emphasised the mine considers it "clearly a public order rather than a labor relations associated matter”.