TUNIS, Sept. 2 (Xinhua) -- One National Guard officer and three terrorists were killed Monday in exchange of fire in central west Tunisia, a regional security source told Xinhua.

On condition of anonymity while waiting for the official report, the source said that the exchanges of fire occurred between units of the National Guard and terrorists in a preventive operation in Hidra district in Kesserine province, which began around 6:30 a.m. local time (0530 GMT) on Monday.

Units of the National Guard opened fire on a terrorist group that attempted to reach the heights of the region from a nearby mountain range.

It's worth noting that this operation coincided with the start of the campaign for the presidential election scheduled for Sept. 15, 2019 when 26 candidates are in the running.