The clashes were the latest to hit the Lebanese port of Tripoli. Repeated outbreaks of violence in the city, the country's second largest, are seen as a spillover from Syria's conflict and has raised fears of an escalation in sectarian tensions in Lebanon.
The fighting in Tripoli started shortly before midnight Friday and intensified Saturday, the officials said on condition of anonymity in line with regulations.
Lebanon and Syria share a complex web of political and sectarian ties and rivalries, which are easily enflamed. Clashes in Tripoli last month killed at least eight people.
The conflict pits Sunni Muslims who support Syrian rebels trying to oust President Bashar Assad against members of the Alawite sect, an offshoot of Shia Islam of which Assad is a member.
Smoke was seen billowing from several apartments near the city's Syria street, the split between the mainly Sunni Bab Tabbaneh neighbourhood and the adjacent, Alawite-majority Jabal Mohsen, on a hill overlooking its rival. The area around Syria street was mostly empty and gunmen were seen roaming the streets.
In Syria, activists said government troops fired shells at Houla, a cluster of farming villages in the central province of Homs where the UN says at least 108 people, including 49 children under the age of ten, were killed on May 25.
The opposition and the government have exchanged accusations over the massacre with each side blaming the other.
Exile opposition leader welcomes military action
Syria has come under deep international isolation since its forces launched a ferocious crackdown on dissent nearly 15 months ago, but the Houla massacre has brought a new urgency in calls to end the crisis.
In Qatar, the head of Syria's largest exile opposition group said Saturday he would welcome Arab military action aimed at ending attacks by Assad's regime against Syrian rebel forces and civilians.
Burhan Ghalioun, the leader of the Syrian National Council, made the comments before a meeting of Arab League foreign ministers. The envoys are to discuss the bloodshed in Syria, including the Houla massacre.
Gulf nations such as Saudi Arabia and Qatar have pledged funds to aid Syria's rebels, but there is no direct evidence that the money is reaching anti-Assad forces or that the rebels are becoming better armed. The Arab League, however, does not appear ready to deploy it own troops. Kofi Annan, the international envoy for Syria, is also in Doha.
As a way to curb the violence in Syria, Arab League chief Nabil Elaraby suggested that the U.N.'s nearly 300-strong observer mission be changed into a peacekeeping role.
"What is needed today is not only observing and investigating but supervising that the violence stops," Elaraby told the meeting.
The deployment of unarmed UN observers is part of Annan's six-point peace plan, which includes a cease-fire that is to lead to talks between the regime and its opponents. The cease-fire, however, has never really taken hold.
'The situation is complex'
Annan warned Arab officials that "the spectre of all-out civil war, with a worrying sectarian dimension, grows by the day," in Syria, and added that the crisis is spilling over to neighbouring countries, an apparent reference to Lebanon.
"The six-point plan is not being implemented, as it must be," Annan said. "The situation is complex, and it takes everyone involved in the crisis to act responsibly if the violence is to stop. But the first responsibility lies with the Syrian Government, and with President Assad."
He called on Assad to implement the plan and "make bold and visible steps immediately."
Meanwhile, since the slaughter in Houla, activists have reported that government troops have shelled the area almost daily. They say many residents have the area for fear of a new massacre.
The Observatory and the Local Coordination Committees also reported shelling and clashes between troops and rebels in the central city of Homs, the southern province of Daraa and some suburbs of the capital Damascus.
One year after the revolt began, the U.N. put the toll at 9,000, but many hundreds more have died since.