Srinagar: The Jammu and Kashmir government appealed for calm on Sunday as six more people died in unending demonstrations against the killing of a top militant leader, taking the death toll to 21 in two days in curfew-bound Kashmir Valley. Shabir Ahmed, 27, was shot and wounded by security forces during a street protest here and died in hospital, becoming the first to be killed outside of north Kashmir since the anti-government protests erupted on Saturday. The incident took place in Batmaloo, a known separatist hub. Fresh firing by security forces in Pulwama district in north Kashmir led to the death of Faiyaz Ahmed Mir. Elsewhere in Pulwama, four CRPF troopers were wounded when militants hurled grenades taking advantage of a street protest. Four other deaths were reported earlier in the day. A mob overran a bullet-proof police vehicle and rolled it down into the Sutlej river at Sangam in Anantnag district, drowning its constable driver while other policemen fled the scene, official sources said. Security forces shot dead two demonstrators at Litter in Pulwama after a mob took to the streets shouting anti-government and pro-freedom slogans, the sources said. Irfan Ahmad Malik, 17, was also killed on Sunday in firing in Pulwama after a curfew-defying mob attacked the security forces, a police official said. The latest fatalities took the death toll in two days of widespread clashes between protesters and security forces in the Kashmir Valley to 21 -- 20 demonstrators and one policeman. Kashmir Valley erupted in anger on Saturday after security forces shot dead Burhan Wani, a top leader of the Hizbul Mujahideen, along with two of his associates on Friday. His funeral was attended by thousands. Most protests have taken place in the northern districts of Anantnag, Pulwama, Kulgam and Shopian. Wani hailed from Pulwama. In most places mobs have attacked police and paramilitary forces with stones, leading to tear-gassing and firing. Taking advantage of the outnumbered security personnel, demonstrators on Sunday set fire to the Sub Divisional Police Officer's office in Pahalgam, a court complex in Dooru and a police post in Qazigund in Kulgam. On Saturday, mobs torched four police stations, two police pickets and a tehsildar's office. There were two incidents of weapon snatching and torching of several vehicles of security forces. Senior officials said three policemen were missing following the violence and nearly 100 security personnel were injured in the street clashes which have crippled the Kashmir Valley and halted the Amarnath Yatra. On Sunday, the Jammu and Kashmir government urged parents of young demonstrators to tell their wards not to take part in protests that were leading to civilian casualties. Education Minister and government spokesman Naeem Akhtar also urged the separatist Hurriyat Conference to help restore calm in the Kashmir Valley, where a separatist campaign has left many thousands dead since 1989. The government said it was also trying to arrange flights to fly out the thousands of tourists stranded in the valley due to the violence. In New Delhi, union Home Minister Rajnath Singh spoke to Jammu and Kashmir Chief Minister Mehbooba Mufti, offering all possible help from New Delhi. Senior officials expressed the hope that the situation in Kashmir would return to normal soon. Four demonstrators, Imtiyaz Ahmad Mandoo, Mashooq Ahmad and Safeer Ahmad (all from Anantnag) and Mohammmad Altaf Rather (Pulwama) who were wounded on Saturday died on Sunday. Eleven people were killed on Saturday. At least 100 protesters were injured on Saturday. They suffered bullet, tear smoke and pellet injuries. Wani was buried in his native Shariefabad village on Saturday where thousands gathered defying curfew restrictions to take part in his funeral prayers. The separatists have called for a valley-wide shutdown till Monday to protest against Wani's killing.