Masked gunmen on a motorcycle fatally wounded a Lebanese soldier Thursday in Tripoli, which has been regularly rocked by sectarian clashes linked to the conflict in Syria, the army said.
Fadi Jbaili, a Sunni Muslim native of the northern port city, was shot in the Boulevard district as he walked to work at around 6:15 am (0415 GMT).
"He was seriously wounded and later succumbed to his injuries," the army statement said.
Tripoli has been rocked by repeated violence linked to the Syria conflict, pitting its Sunni majority, who largely support the rebels, against the Alawite minority, who back their co-religionist President Bashar al-Assad.
It was the fourth case in which a soldier has been murdered this way in Tripoli since February, but officials were unclear about the motive.
A security official told AFP a "Syrian suspected of involvement" had been arrested after being found hiding in a building near the site of the shooting.
The incident came a day after gunmen killed an Alawite, triggering renewed sectarian clashes that killed an 11-year-old boy in a Sunni neighbourhood.
Tensions between the two districts go back decades but have been exacerbated by the three-year-old conflict in neighbouring Syria.
In December, Human Rights Watch said a government security plan for Tripoli "should specifically include measures to protect Alawite residents and their property".
On Thursday, the government ordered the army and security forces to control the security situation in Tripoli and to seize arms caches in the city.
Alawites make up only 11 percent of the city's population, while Sunnis account for 80 percent.