KABUL, July 30 (Xinhua) -- Four security guards of a private company were killed Thursday as a roadside bomb struck their vehicle in the volatile Helmand province of southern Afghanistan, a press release of Interior Ministry said.

    "Four private security guards were killed in a roadside mine explosion planted by the enemies of Afghanistan in Nahar-Saraj district of Helmand province today," the press release said.

    This is a local security company named Hamayon PSC and all the victims were Afghans.

    Similar attack on the same company couple of days ago in Gereshk district of Helmand left eight security guards dead and eight others wounded, the press release further said.