Five pilgrims from Rajasthan were injured when militants hurled a grenade at their bus at Beehama in Ganderbal, 23 kilometres from Srinagar, on Wednesday.
This is the first attack on Amarnath pilgrims in 2006.
Subsequently, the Srinagar-Baltal road, which is the main route that the pilgrims take, has been shut.
Officials said the bus, carrying 40 passengers, was returning to Srinagar from Baltal base camp.
The injured were immediately rushed to the Soura Medical Institute.
No militant outfit has so far claimed responsibility.
The passengers who escaped said unidentified persons hurled the grenade inside the vehicle from a window when its driver slowed down.
"I was getting off the vehicle at Beehama chowk to fetch water when the blast occurred," Ajay Soni, a passenger, told PTI.
The two-month annual Amarnath yatra commenced on June 11 amid tight security. The incident comes close on the heels of three grenade attacks on tourist buses at Batapora and Dalgate in Srinagar in May, which left five tourists dead and over 20 others injured.
With PTI inputs