Kabul, Afghanistan (CNN) -- A vehicle headed to a wedding party and a school bus carrying students hit insurgent-planted bombs in southwestern Afghanistan on Wednesday, killing 22 people and wounding 20, authorities said.

The incidents, which occurred in different districts of Nimruz province, are the latest in Afghanistan to result from improvised explosive devices -- regarded as the top killer of civilians in the war-weary nation.

Thirteen members of a family were killed and 10 people were injured when a vehicle struck a road mine, said Nimruz police chief Abdul Jabar Pordeli. The people had been headed from Nimruz to Herat in western Afghanistan as part of a wedding party.

Five women, five children and three men died, said Pordeli, who added that the bride may have been inside the vehicle.

In another part of Nimruz, a school bus carrying female students struck an explosive device, killing nine and wounding 10, NATO's International Security Assistance Force said.

Eight of the nine dead were children.

"This is a horrific tragedy and demonstrates the indiscriminate killing of civilians from IEDs planted by insurgents. ISAF condemns this violence in the strongest possible terms," said U.S. Army Col. Rafael Torres, ISAF spokesman.

"Our thoughts and concerns are with the families of this senseless crime."

And in southern Afghanistan, an ISAF service member died in an IED attack on Wednesday.