Those killed were petroleum company employees on board a bus in Mazar-i-Sharif, according to a local official.
At least seven people have been killed in a roadside blast in northern Afghanistan, according to local officials, the latest attack in the violence-racked country.
Those killed in the 7am (03:00 GMT) blast on Tuesday in the city of Mazar-i-Sharif included employees of a petroleum company on a bus, said the local officials.
“The bomb was placed in a cart by the roadside. It was detonated as the bus arrived,” said Asif Waziri, of the Balkh police department in Mazar-i-Sharif.
The northern Balkh province contains one of the country’s main dry ports at the town of Hairatan near the border with Uzbekistan, containing rail and road links to Central Asia.
It was not immediately clear who was behind the attack, which comes amid repeated pledges from the Taliban government to bring security to Afghanistan following decades of war.
The Taliban government swept to power in August last year amid a withdrawal by United States-led foreign troops, who had invaded the country and toppled the group from power in 2001.
Last month, at least 19 people were killed and 24 others wounded by a blast at a school in Aybak, a city in Samangan province that abuts Balkh province.
In May, at least nine people were killed in a series of explosions in Mazar-i-Sharif, while two others were killed in a simultaneous attack at a mosque in the capital, Kabul.
ISIL (ISIS) – the Taliban’s main rival in Afghanistan – had claimed responsibility for the attack in Mazar-i-Sharif, but not for the Kabul blast.
Recent violence has also included a suicide bombing that killed four at a mosque at Afghanistan’s interior ministry building complex in October.