Two skiffs with two armed pirates in each skiff chased and closed in onto a tanker underway. Alarm raised and crew mustered. When the skiffs closed in to around 100m from the tanker the pirates fired upon the tanker. The armed guards onboard the tanker returned fire, resulting in the pirates aborting the attack and moving away. All crew safe. Ship sustained minor damage due to the firing. Ladders sighted in the skiffs.