BEIRUT — Lebanese state media said Tuesday that clashes have broken out in a border town held by Islamic extremists from neighboring Syria after a negotiated truce collapsed overnight.

The ceasefire, mediated by Muslim clerics, was meant to help end four days of fighting in the town of Arsal and allow for negotiations for the release of captive Lebanese soldiers.

The National News Agency says fighting broke out again after militants opened fire on troops on early Wednesday.

Syrian militants overran Arsal on Saturday, seizing Lebanese army positions and capturing a number of soldiers and policemen. It has been the most serious spillover yet of Syrian violence into tiny Lebanon.

So far, 17 Lebanese troops have been killed and at least 22 soldiers and an unknown number of policemen have been declared as missing.

The fighting in Arsal marks the first time that the rebels battling Syrian President Bashar Assad have carried out a large-scale incursion into Lebanon, raising fears that the tiny country is being further drawn into its larger neighbor’s bloody civil war.

In an apparent gesture of goodwill, militants released three policemen they had been holding captive on Tuesday. The Lebanese security official said the army later agreed to a “humanitarian” 24-hour truce to give way to negotiations for more such actions and to ease the suffering inside the town.

“We will return fire if our positions are fired upon,” the official said. He spoke on condition of anonymity in line with military regulations.

Early Wednesday, the short-lived truce collapsed.

Meanwhile, in a possible sign of the conflict spreading further into Lebanon, gunmen opened fire at a bus carrying soldiers in the northern city of Tripoli wounding seven early Tuesday, the army said. Gunmen also fired on several army positions in the city overnight, and an eight-year-old girl was killed when a bullet struck her in the head.

Like Arsal, Tripoli is predominantly Sunni and many residents back the overwhelmingly Sunni rebels in Syria trying to overthrow Assad.

Lebanon’s powerful Hezbollah militia, however, not only backs the government of Assad, but has also fought in Syria side by side with his forces.

The Syrian government has seized nearly all the strategic Qalamoun region bordering Arsal with the help of Hezbollah fighters.

Anti-Hezbollah Lebanese politicians have accused the group of being responsible for the spillover in Arsal. Members of the Future Movement, Lebanon’s main Sunni party demanded that Hezbollah withdraw from Syria, accusing it of dragging terrorists to Lebanon because of its involvement in the civil war next door.

The main Western-backed Syrian opposition group, the Syrian National Coalition, also accused Hezbollah of shelling Syrian refugees in Arsal.

However, there has so far been no evidence of the group fighting in Arsal, and Hezbollah issued a statement Tuesday denying it was involved. “Confronting the armed terrorists and protecting civilians is the responsibility of the Lebanese army exclusively,” it said.

Copyright 2014 The Associated Press.