"Two Indian engineers were killed. Several other people including three Indians were injured."
Besides the Indians, "the wounded included their Afghan driver and a policemen", Azad said.
Yousuf Ahmadi, a purported spokesman for the Taliban, claimed responsibility but gave a different version of the attack.
He said at first two mines planted by fighters were detonated, after which a bomber blew himself up.
He said the attack "was carried out by our mujahidin".
"First they detonated two mines that we had buried in the area," Ahmadi said.
"After police and the Indians gathered there one of our devoted members carried out a suicide bombing."
In a separate development, government forces backed by foreign military aircraft killed 24 Taliban fighters in an overnight raid in the south, according to an Afghan official said on Saturday.
The operation in the province of Zabul was designed to secure a key highway to the capital Kabul, he said.
"We had an operation against the Taliban last night," Gulab Shah Alikhail, Zabul's deputy governor, told the AFP news agency.
"During the operation, in which foreign military's air force was used, 24 Taliban were killed and eight others were injured."
Alikhail said the operation started late on Friday and continued through early Saturday.
But a spokesman for the Taliban told Al Jazeera on Saturday that no such raid had taken place.
The latest incidents came at the end of a week of Taliban attacks and government raids.
A suicide-car bombing on Thursday in Kandahar, another southern province, killed eight civilians.
On Tuesday, 17 civilian road builders were killed after the Taliban attacked their convoy near the capital town of Qalat.
Three Taliban fighters were killed in a subsequent operation against the attackers by Afghan and foreign security forces.