The double bombing came less than two weeks after gunmen attacked the American University in Kabul, killing 13 people.
Many in the country rely on old and rickety passenger vehicles and road accidents with high casualty rates are common.
"This tragic event in Helmand province reminds us that Afghanistan remains a dangerous place."
At least two attackers are killed, a police official said
"Many students jumped from the second floor, some broke their legs and some hurt their head trying to escape."
India told the Afghans that it would do whatever it could to meet the security forces' requirements
"Sometimes we fly from 7 a.m. until 6 p.m. We have a limit and if we fly more we become...
"It is not the regular Taliban force with a pair of sandals and an AK-47... They are better trained and...
It is the second U.S. killing of a prominent militant in the region in months.
The kidnappers were wearing Afghan security uniforms
A photo shows a close up views of identification cards for a U.S. Army soldier, Specialist Ryan Larson.
Top photos from the past week.