KANDAHAR, Afghanistan, March 11 (Xinhua) -- Two Afghan civilians were wounded after NATO and U.S.-led coalition forces opened fire in southern province of Kandahar on Sunday, a local official said.

"Initially an explosion went off near a mobile patrol of coalition forces Sunday morning near Kandahar airport. The foreign security force secured the area and warned people to keep away from the site," a provincial security source told Xinhua.

Some passersby ignored the warning of security force and tried to pass the area and two civilians were wounded by ensuing gunshots, he said.

It was not immediately known if the blast causes casualties or damage. The source added that an investigation was launched into the incident.

The main U.S. and NATO military base in southern Afghanistan is located in Kandahar airport.

Security situation has been improving in Kandahar, the former stronghold of Taliban, over the last months, as security forces have conducted search and cordon operations across the province. But the militants attack government interests in the province from time to time.