A bomb exploded in a bazaar in western Afghanistan crowded with people shopping to celebrate the end of the Muslim holy month of Ramadan, killing four civilians, an official said.
A dozen other people were wounded on Saturday morning by the bomb which was placed under a bridge in Shindand district of Herat province, provincial spokesman Mohiuddin Noori told the AFP news agency.
It came after a bicycle bomb Wednesday wounded at least 14 people at a busy market in Herat city, the capital of the province.
"This morning a bomb placed under a bridge in a bazaar exploded and killed four civilians and wounded 12 including three police", the spokesman told AFP, adding an investigation was under way.
Abdul Rahouf Ahmadi, a spokesman for security forces in western Afghanistan, confirmed the casualties and blamed "enemies of Afghanistan", a term used by officials to refer to Taliban insurgents fighting foreign forces in the country.
A recent United Nations report found the number of Afghan civilian casualties had fallen by 15 percent in the first half of 2012. However, the country has recently been witnessing an increase in attacks on civilians.
On Tuesday, a series of suicide and bomb attacks killed up to 50 people across the war-torn country.
The bloodshed came as the nation prepared to celebrate the end Ramadan, with many of the victims shopping in bazaars for Eid celebrations.