At least 40 people were killed and 83 injured on Friday when suicide attackers stormed a mosque near army headquarters in Pakistan's Rawalpindi city spraying bullets on hundreds of Friday worshippers, including military personnel, and hurling grenades before blowing themselves up.The attackers, who used ladders to climb over the walls of the Jamia Masjid near Parade Lane, lobbed grenades and fired indiscriminately at worshippers. They also exchanged fire with the mosque's security guards.There was confusion over the total number of terrorists involved in the attack.Some witnesses said seven to eight gunmen stormed the mosque, which was packed with Friday worshippers including serving and retired military personnel, while police and army officials put the number of assailants at five to six.