An AFP journalist in Tripoli reported the lull after three days of heavy clashes in Tripoli, the country's second biggest city, even as the army vowed to crush the militants.But Syria's Al-Qaeda branch renewed a threat that it will execute one of 27 Lebanese soldiers it has held hostage since August unless the military halts its operations in Tripoli.

The coastal city has seen repeated clashes between Sunni militants sympathetic to rebel fighters in neighboring Syria and Alawites.The Sunnis have recently focused their attacks on the army and Shiites citizens. The latest clashes erupted on Friday at the city's historic market, which is a major tourist attraction.

On Sunday army mortar fire pounded the impoverished, outlying neighborhood of exterimist bastion Bab al-Tebbaneh, where the gunmen were pushed back and cornered.

Five civilians have been killed in three days, among them a child and two adults. Army Command – Orientation Directorate also declared 4 officer and 1 soldier “martyred” Sunday during the clashes with the militants in Tripoli and the nearby regions.

After pleas from residents and mediation by clerics, the army allowed thousands of civilians who had been caught in the crossfire for hours to flee Bab al-Tebbaneh.The AFP journalist on the spot described chaotic scenes as people of all ages left their ravaged neighborhood.

It is unclear how long the informal humanitarian truce will last, and the army has said it has no intention on letting up in the fight."We are going through with this operation to the end," a military source said.

Bab al-Tebbaneh is home to some 100,000 people, while the parts of the neighborhood where the fighting is worst is usually inhabited by some 15,000.The AFP journalist said that even in areas far from the fighting, the streets were empty, with people too fearful to leave their homes.

Execution threat

Earlier, the army said gunmen ambushed a patrol north of Tripoli, killing four soldiers."This afternoon, an army unit was targeted by a terrorist group while deploying in Duhur al-Mohammara. A clash broke out, which caused several casualties in the militants' ranks, while four soldiers including two officers were martyred," said a statement.

Meanwhile a soldier kidnapped at the weekend was released after mediation by officials and clerics, a security source said. A second soldier kidnapped on Sunday was still being held by the gunmen.

Nusra Front -- Al-Qaeda's Syrian affiliate -- meanwhile threatened to kill at dawn on Monday a Lebanese soldier it captured in August during a bloody battle in restive Arsal unless the army halts its Tripoli operations.

Al-Nusra Front has previously executed one captive Lebanese soldier. The latest threat, issued via the group's Twitter account, came after two previous warnings on Sunday, which it apparently backtracked on.

Both Al-Nusra and rival ISIS group captured 30 Lebanese soldiers and police in August around the eastern town of Arsal, close to the Syrian border.They have since executed two of them.

The August fighting in Arsal -- a Sunni enclave within the mainly Shiite Bekaa Valley border region -- was the most serious in Lebanon since the Syrian conflict erupted in March 2011.

Today at the 4th day of unrest in Tripoli in the north of Lebanon, local media reporting Ongoing Battle in the some neighbourhoods of the city.

Lebanese Army insists on ending this ‘abnormal’ situation in Tripoli’s Bab al-Tabbaneh, stressing that this will be no truce for ceasefire, a military source reported to Al Joumhouria Daily.

On Bab al-Tabbaneh – flashpoint of clashes -- extremist militant targeted army patrol and troops respond to sources of fire.Fierce clashes also erupted close to Massoud Mosque in Bab al-Tabbaneh on Monday.

On Sunday Army units carried out a widespread deployment in old Sidon and at the gate of Palestinian Refugee Camps, as part of precautionary security measures implemented in various regions.

In this operation an Army Intelligence Patrol unit arrested a Palestinian suspect, who attempted to escape at Army checkpoint. Yesterday also Lebanese Army units arrested Syrian national, Ahmed Mohammed Shehab for involvement in the kidnapping of Lebanese soldiers in Arsal last month.

Shehab was travelling from Beirut to the Bekaa with fake Lebanese Identity card, he was stopped at the checkpoint in Dahr al-Baydar, where he was identified by security officers.

According to available information, Shehab has admitted to taking part in the kidnapping of Lebanese soldiers and was taken to the Defense Ministry for further investigation.