Kabul, Afghanistan (CNN) -- A police trainer and a civilian interpreter were killed and two policemen were wounded Saturday when their vehicle hit a roadside bomb in western Afghanistan, a police spokesman said.
It happened around 7:30 a.m. (11 p.m. ET Friday) in western Herat province as the group was on its way to the Adraskan police training center where they were working, said Abdul Rauf Ahmadi, a spokesman for the Afghan police commander in the west of Afghanistan.
The explosion happened the same day as NATO's handover of a police training academy in the city of Herat, but the two events were miles apart and unrelated.
U.S.-led international forces are continuing to hand security responsibilities over to Afghan forces as the withdrawal of U.S. troops proceeds.
There are about 68,000 American troops still in Afghanistan, but combat operations are scheduled to end next year and the entire international force is scheduled to withdraw by the end of 2014.
After that, a new NATO mission will advise, train, and assist an estimated 350,000-strong Afghan force, NATO Secretary-General Anders Fogh Rasmussen has said.