QUETTA, Pakistan (AP) — Pakistani intelligence officials say militants killed four troops escorting an election convoy in the volatile southwestern province of Baluchistan.

The attack, on the eve of elections, is the latest violence ahead of the balloting.

Two intelligence officials say the troops were escorting a convoy with election staffers and voting material on Tuesday in the district of Turbat when they came under attack.

The officials say the assailants first fired grenades as the convoy passed through the Niwano area, then shot at the troops. Three army soldiers and a member of the paramilitary force were killed.

Thirteen people — eight soldiers, a member of the paramilitary force and four civilians — were wounded.

Both officials spoke on condition of anonymity because they were not authorized to speak to the media.