U.S. Under Secretary of State for Political Affairs Victoria Nuland met with Lebanese leaders on Thursday, on a visit whose schedule was thrown off by the deadly Tayyouneh clashes -- the most dangerous round of sectarian fighting that the country has witnessed since 2008.

Speaking at a press conference that followed her meetings with the country’s leaders, Nuland offered condolences on behalf of the American people for “the tragic loss of life” in the clashes.

Lebanon prepared to bury the victims of its deadliest sectarian unrest in years Friday after gunfire gripped the Tayyouneh-Ain el-Rummaneh area for hours and revived the ghosts of the civil war.

Seven people were killed and dozens wounded Thursday when violence erupted following a rally by Hizbullah and Amal Movement protesters demanding the removal of the judge investigating last year's port blast.

Hizbullah and Amal on Thursday openly accused the Lebanese Forces of launching an “armed attack” on their supporters in the Tayyouneh area, which had during the day witnessed hours-long armed clashes reminiscent of the beginning of the 1975-1990 civil war.

The United States on Thursday urged an easing of tensions in Lebanon after deadly violence in a Beirut suburb sparked fears of a return to sectarian strife.

U.N. Special Coordinator for Lebanon Joanna Wronecka expressed "deep concern" Thursday over the outbreaks of violence that took place in and around Tayyouneh and resulted in several deaths and injuries.

Condemning the "use of armed violence outside of state authority," she underscored the need for restraint and for maintaining calm and stability and ensuring the protection of civilians.

Amal Movement and Hizbullah accused "armed and organized groups" of assaulting their supporters in Tayyouneh, in a joint statement Thursday.

President Michel Aoun has made calls to follow up on the developments of the Tayyouneh clashes “in order to address the situation and take the necessary action to restore calm to the region,” the Presidency said Thursday.

Aoun called Prime Minister Najib Miqati, ministers of defense and interior Maurice Slim and Bassam Mawlawi, and Army Commander General Joseph Aoun.

Former Prime Minister Hassan Diab returned to Beirut on Wednesday evening, amid a political campaign led by Hizbullah and Amal against Lead investigator in Beirut port blast, judge Tarek Bitar.

Bitar in August subpoenaed Diab for interrogation on September 20 after he failed to show up for questioning.

Heavy fighting claimed at least six lives and left dozens wounded in and around the Tayyouneh area on Thursday as an escalation of tensions around last year's massive portside explosion turned parts of Beirut's southern edge into a war-zone.

The army deployed tanks and troops to quell street battles that sparked memories of the 1975-1990 civil war for a city already traumatized by last year's blast disaster and Lebanon's worst-ever economic crisis.

Lebanese Forces party chief Samir Geagea asked Wednesday the government, President Michel Aoun and Prime Minister Najib Miqati not to "bow to Hizbullah's intimidation" concerning the dismissal of lead investigator into the port blast case, Judge Tarek Bitar.

“If they stop the investigations, they must resign immediately,” he said.