A retired U.S. Customs and Border Protection officer was killed and three other U.S. customs workers were wounded in a suicide bombing earlier this week in southern Afghanistan.

U.S. Homeland Security Secretary Janet Napolitano said in a statement released Tuesday in Washington that David Hillman, a retired customs officer who had worked for the U.S. government for 30 years, died in the blast Monday at the Inland Customs Warehouse in Kandahar.

Afghan police said the suicide bomber detonated a cache of explosives inside the city's customs house compound during a visit by NATO forces.

The Taliban in Kandahar are attacking officials and others who support pro-government forces.

Earlier this month, a suicide bomber killed the deputy governor of Kandahar province.