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

“We join Lebanese authorities in their call for calm, their calls for a de-escalation of tensions,” State Department spokesman Ned Price told reporters.

At least six people were killed after shots were fired at a demonstration by the Shiite Muslim movements Hezbollah and Amal, who were rallying against a judge investigating a massive blast last year at the Beirut port.

The US declined comment on who was responsible but reiterated its criticism of Hezbollah, an Iranian-backed group which Washington considers a terrorist group.

“The future of Lebanon’s democracy depends on the ability of its citizens to address the difficult issues with confidence in the rule of law,” Price said.

“Judges must be free from violence. They must be free of threats. They must be free of intimidation, including that of Hezbollah,” he said.

Hezbollah and Amal blamed their foe the Lebanese Forces, a Christian party in the religiously divided nation.