The convoy was attacked before dawn outside the town of Dera Murad Jamali, some 400 kilometres southeast of Quetta, the capital of restive Baluchistan province, local administration chief Abdul Fatah Khajjak said.
"The attackers, riding in a car, opened fire on oil tankers parked at a petrol pump waiting for daybreak to resume their journey to Afghanistan," Khajjak said.
Some 16 oil tankers caught fire, but two more parked a distance away were undamaged, he said. One of the fuel tanker staff was wounded by the gunfire.
The gunmen fled after the attack and no one had so far claimed responsibility, Khajjak said. A security official also confirmed the attack.
In October, gunmen torched 29 oil tankers also bound for Afghanistan in the remote Mitri area, 180 kilometres southeast of Quetta.
Baluchistan, which borders both Iran and Afghanistan, is torn by Islamist militancy, sectarian violence and a separatist insurgency by rebels seeking political autonomy and a greater share of profits from natural resources.
Most supplies and equipment required by foreign troops in Afghanistan are shipped through Pakistan, although US troops increasingly use alternative routes through central Asia.
Pakistan shut its main northwestern border crossing to NATO supply vehicles on 30 September for 11 days after a cross-border NATO helicopter assault killed two Pakistani soldiers.
Scores of NATO supply vehicles were destroyed in gun and arson attacks while the border crossing was shut, with Taliban militants determined to disrupt the route and avenge US drone strikes in Pakistan's tribal belt.