Shooting between Sunni and Shia Muslim fighters near the Ein el-Helweh Palestinian refugee camp in southern Lebanon has left at least four people killed and seven others wounded, security officials say.The officials said the clashes on Sunday between followers of Salafi leader, Ahmad al-Assir, and members of the armed Shia group Hezbollah broke out after Shia religious banners for Ashoura were not removed in the port city of Sidon.The officials, who spoke on condition of anonymity, said al-Assir’s bodyguard was killed in Sunday’s shooting, and the wounded included a Hezbollah commander.Assir had given an ultimatum to Hezbollah supporters to take down all posters promoting the Shia group, but that they refused.Supporters of Assir then removed a poster of Hassan Nasrallah, the Hezbollah chief  who is a staunch ally of Syria’s President Bashar al-Assad, and clashes ensued.Al Jazeera’s Rula Amin, reporting from Beirut, said that the "deadline” was today for removing those posters."Hezbollah took down most of the banners and were not interested in a clash,” she said. "Gunfire erupted but it’s hard to pin down who started firing.”She said the Lebanese army had already deployed in the mostly Sunni city, which has little Hezbollah presence but is considered the gateway to southern Lebanon.Mikati calls for calmUnknown before the outbreak of the uprising in neighbouring Syria last year, Assir rose to prominence for his outspoken opposition to the Assad regime and his calls for disarming Hezbollah, the strongest military force in the country.In response to Sunday’s killings, Najib Mikati, Lebanese prime minister, called an emergency meeting with Marwan Charbel, interior minister, and the regional security council for southern Lebanon.Afterwards, Mikati said he had requested the army and security agencies to take prompt measures to bring the situation under control and arrest those behind the violence."We call on everyone to remain calm and execute restraint at this critical and delicate juncture,” Mikati said.Lebanon’s opposition coalition has accused Mikati, a prominent Sunni figure, of complacency in leading a Hezbollah-controlled government.