The Jammu and Kashmir [Images] police have arrested four persons on the basis of information provided by a person who was apprehended by locals after he threw a grenade on one of the targets on July 11.

Eight tourists from West Bengal were killed in the attack and scores were injured.

"We have arrested four persons but we would not be able to give the names at this stage. The mastermind behind these attacks is a Pakistani-trained terrorist Mudassar.

"We have released his sketches to the media," Jammu and Kashmir police chief Gopal Sharma told rediff.com.

The sudden spurt in terrorism in the valley comes at a time when tourists have been flocking to the state things appeared to be back to normal in the troubled state.

An attack at Gulmarg on July 12 forced the tourists to pack their bags and leave Srinagar [Images].

According to sources in the valley, the terrorists had an unwritten accord with the tour operators that they would not target the tourists and in return would be paid a certain sum.

It is said that the tour operators breached the contract at a time when virtually every room and houseboat was occupied.

"Some tourists have left Srinagar in last two days but the real figure would emerge only on Friday," Sharma conceded.