Unknown insurgents killed two Afghan security guards in an attack on a compound housing NATO contractors in Afghanistan's western Herat province.

Thursday's attack began with a suicide car bombing outside the offices of Monaco-based ES-KO. Gunmen then stormed the offices and launched an hours-long gunbattle with Afghan security forces.

NATO said it provided air and ground assistance in response to the attack, which took place near its regional headquarters in the area. Several people were wounded in the assault, while all five attackers were either shot dead or died in the initial explosion.

ES-KO's website says the company has provided food services to coalition forces in Afghanistan and built a runway at Herat's airport near where Thursday's attack took place.

NATO began transferring security responsibility in Herat's provincial capital to Afghan forces in July.

All international combat troops are set to complete their withdrawal from the country and transfer full security control to their Afghan counterparts by the end of 2014.

In a similar attack Monday, a suicide bomber blew up a car near offices used by the United Nations refugee agency in the southern city Kandahar. Three gunmen then rushed into the area, sparking a gun battle. The Taliban claimed responsibility for the combined attack, which killed five people, including three U.N. employees.