Tensions between the rebels and tribes in the country’s north have been rising in the Harf Sufyan area for months, and exploded after rebels attacked a tribal leader’s home on Friday, killing three of his followers in an explosion.

The Sanaa government, with agreement of the rebels, sent troops to the area on Sunday to restore calm. Rebels said gunfire erupted when the contingent of several hundred soldiers turned out to be much larger than the several dozen they had expected.

“Troops were sent to Al-Amshia to secure the Sanaa-Saada road, but the rebels prevented their arrival and opened fire in their direction,” a provincial official told Reuters, referring to the rebels by the tribal name of their leader.

The rebels said they played no role in the shooting, and that civilian gunmen alarmed by the troop influx had opened fire. No injuries were reported, and the troops were prevented from entering the area.

Yemen agreed a truce with the rebels in February to halt a northern war that has raged on and off since 2004, displaced 350,000 people.

The cease-fire has largely held. But sporadic violence threatens to destabilize further the Arabian Peninsula state that is also trying to subdue southern separatism and fight a resurgent arm of Al-Qaeda.

Sanaa also accused the rebels of delaying implementing terms of the truce with the rebels, who complain of religious and economic discrimination by the state.

“Despite the halting of military operations ... and the rebels committing to the truce, they have been avoiding the full implementation,” an official, who is part of a committee overseeing the truce, told the state news agency SABA.

SABA added that the truce committee remained committed to achieving peace in the north, where last month Yemen accused rebels of killing a government soldier.

The government says rebels have been slow to hand over weapons, including guns, tanks and mortars, and to withdraw from positions in the north. The rebels counter that the state has delayed freeing all rebel prisoners as agreed under the terms of the truce.

In another development, a court said it will on Wednesday announce a verdict in the trial of two alleged Al-Qaeda members accused of being part of an armed gang that killed military and security officials.

Prosecutors, wrapping up the trial on Sunday, demanded death sentences for Mansour Saleh Salem Daleel, 18, and Mubarak Ali Hadi Al-Shabwani, 23, who were arrested on Dec. 11 in eastern Marib province.

The two defendants are being tried by a Sanaa court that specializes in terrorism cases.