BEIRUT,(Reuters) – Hezbollah, Lebanon’s most powerful faction, on Monday demanded to know who was behind shooting that killed eight opposition supporters in some of Beirut’s worst street violence since the 1975-90 civil war.

The pro-Syrian group said any cover up would be a threat “to stability and civil peace” in Lebanon. The bloodshed has fuelled fears of factional violence unless a 14-month political crisis is resolved.

Shi’ite Muslim Hezbollah has been leading an opposition campaign against Prime Minister Fouad Siniora’s U.S.-backed government. The political stalemate has left Lebanon without a president since November.

Security sources said at least 29 people were wounded in the violence on Sunday after the army moved to break up a protest by anti-government activists against power cuts. One of the wounded later died in hospital. “Did those who fell as martyrs and were wounded fall by the army’s bullets, and if so, who issued the order for the soldiers to fire?” Hezbollah asked in a statement. “Or was there another party, and who was it?” The group said it held the authorities responsible for “every drop of blood spilt”.

Witnesses said soldiers had fired to break up the demonstration. The army, whose leader has been agreed as the next president, has launched an inquiry into who was behind the killings.

A ninth person was killed in south Lebanon when hit by a car during a protest against the shootings, security sources said.

Hezbollah and Amal, another pro-Syrian Shi’ite party, decided to bury the dead separately on Monday, avoiding a mass funeral that could further raise tensions.

Schools and universities were closed to mark a national day of mourning called by the government.

The violence close to both Shi’ite and Christian areas was the worst in Beirut since supporters of the anti-Syrian governing coalition and its pro-Damascus rivals clashed a year ago.

The political crisis has deepened divisions between Sunni and Shi’ite Muslims and Christians loyal to rival leaders.

Hezbollah, which has a highly trained guerrilla army, has consistently stated its opposition to any civil conflict and says its weapons are directed only at Israel.

The army has been widely credited with keeping the peace among Lebanese during three years of political turbulence since the killing of former Prime Minister Rafik al-Hariri in 2005.

It has stayed neutral in the political conflict and policed demonstrations by both pro- and anti-Syrian groups.

Army chief General Michel Suleiman had been agreed by rival leaders as the candidate to fill the presidency, a post empty since the term of the pro-Syrian Emile Lahoud ended. But Suleiman’s election by parliament has been delayed by a dispute between the sides over the make-up of a new government.

Commentator Sateh Noureddin said any suggestion the army was behind the deaths would strip it of its status as a neutral guarantor of civil peace. “In our history, the first sign of a new civil war is a loss in confidence in the Lebanese army,” he told Reuters.