(CNN) -- In three separate attacks, militants on motorcycles torched trucks in Pakistan on Friday that were taking fuel and supplies to NATO troops in Afghanistan, police said.

In all three attacks, militants cut off the moving trucks and opened fire, said police official Muhammad Ashraf.

The attacks happened in the southwestern province of Baluchistan. They targeted three fuel tankers and a supply truck.

A driver of one the trucks was killed and a passenger was injured, police said.

The attacks come less than a week after militants set fire to at least 10 NATO fuel tankers in the province.

Militants in Pakistan increasingly have been trying to undermine NATO forces in Afghanistan by attacking their supply trucks.

NATO officials have downplayed the impact of the attacks on operations in Afghanistan, but they have also started to use more alternate routes in countries such as Kazakhstan and Uzbekistan.