BEIRUT, Aug 2 (Reuters) - The Lebanese army detained two men over an attack on Shi"ite mourners at a funeral where three people were killed, a security source said, after the Shi"ite group Hezbollah demanded the perpetrators be arrestedto avoid civil strife. The shooting in Khaldeh, a town just south of Beirut where tensions between Shi"ite and Sunni Muslimshave been simmering, prompted warningsagainst sectarian bloodshed with Lebanon already suffering destabilising financial and political crises. The heavily armed, Iranian-backed Hezbollah called the attack a "great aggression" and warned of serious consequences if the attackers were not detained. The attack targeted the funeral of Hezbollah member Ali Shibli, shot dead a day earlierat a wedding. read more Sunni Arab tribes claimed responsibility, saying it was in revenge for the killing of one of their members last year in Khaldeh. Army intelligence stormed the homes of a number of wanted people and detained a person involved in the funeral attack, the army said. A second suspect was also detained, the security source said. Soldiers deployed heavily in Khaldeh, where an armoured vehicle was stationed outside Shibli"s house and bullet shell casings could be seen on the ground. The army said gunmen had opened fire on the funeral cortege, leading to clashes. Hezbollah has said it is seeking to maintain calm but could not control everyone angered by the attack, which it has called a planned ambush. "You don"t want strife, then come and surrender those killers to the state," Hassan Fadlallah, a Hezbollah MP, told al-Jadeed TV on Sunday. Lebanon is already suffering the greatest threat to its stability since the 1975-90 civil war due to the crippling financial crisis that has sunk the currency by more than 90%. This week also marks the first anniversary of the devastating Aug. 4 Beirut port explosion. read more "STRIFE" Sunni politician Saad al-Hariri"s party said on Sunday it was in contact with Sunni tribes in the area to work for calm. "What happened in Khaldeh confirms the blatant absence of the logic of the state and that the language of uncontrolled and illegitimate arms is the one prevailing," Fouad Makhzoumi, an independent Sunni MP, wrote on Twitter. "We are afraid of the country being dragged to strife." Khaldeh has been a flashpoint as protesters have often blocked the highway used by many Shi"ites to travel to and from their homes in the south. The Shi"ite Amal Movement, a Hezbollah ally, said the funeral attack was a threat to stability and urged the army to take control of the highway. Shibli"s coffin was draped in a Hezbollah flag at his funeral in the town of Kunin in southern Lebanon. Hezbollah fighters wearing camouflage and red berets were in attendance, footage on Hezbollah"s al-Manar TV showed.