Taliban fighters killed 15 Afghan guards working for a private security company who were escorting a convoy of fuel tankers driving through western Afghanistan, an official said Tuesday. Six Taliban were killed in the ensuing fight. Between six and eight vehicles of a private security company were guarding a convoy of fuel tankers when the Taliban attacked early Tuesday, said Farah Gov. Muhaidin Baluch. Fifteen guards were killed and five were wounded, Baluch said. One fuel tanker was set on fire, he said. Baluch said the guards worked for USPI - Texas-based US Security and Protection. No officials could be reached for comment at USPI's Houston, Texas, headquarters or at the company's offices in Kabul. However, two USPI employees contacted by The Associated Press who asked not to be identified because they were not authorized to talk to the media said USPI guards were not involved. One employee said Afghan officials in the south tend to identify all security companies as USPI, even when they are not. Gen. Khail Buz Sherzai, the provincial police chief, said officials were not completely sure of the name of the security company. Baluch said the tankers were traveling from the western city of Herat to a military outpost in Lashkar Gah, the provincial capital of Helmand province, the region that has seen the heaviest fighting in Afghanistan this year. Meanwhile, in southern Afghanistan, a US-led coalition airstrike on a Taliban commander and subsequent operation in Helmand province's Kajaki district killed several militants Monday, the coalition said in a statement. The strike targeted a Taliban commander in Kajaki district of Helmand province, involved in the movement of foreign fighters and suicide bombers, the statement said. In neighboring Uruzgan province, Afghan and US-led coalition forces clashed with insurgents in the village of Deh Rawod on Monday, another coalition statement said. The joint forces were patrolling when a group of 16 insurgents attacked with rocket-propelled grenades and other weapons. The Afghan and US forces fired back and called in airstrikes, "effectively eliminating the enemy fighting position." Elsewhere in Farah, fighting between police and militants in Kaki Safe district left two of the militants dead, said Gen. Khail Buz Sherzai, the provincial police chief. More than 6,300 people, mostly militants, have been killed in insurgency related violence in Afghanistan this year, according to an Associated Press count based on official figures. The country has also seen a record number of suicide bomb attacks - more than 140 - in 2007.