Pakistani Prime Minister Imran Khan on Tuesday accused India of being behind a shooting and grenade attack on the Pakistani stock exchange that left seven people dead in Karachi a day earlier. India said on Monday that it had nothing to do with the assault. "There is no doubt that India is behind the attack," Mr Khan said in his address to parliament. "For the last two months, my Cabinet knew [there would be an attack], I had informed my ministers. All our agencies were on high alert." A group armed with guns and grenades attacked the Pakistan Stock Exchange in the city of Karachi on Monday in a bid to take hostages, killing two guards and a policeman before security forces killed all four attackers, security officials said. Separatist insurgents from the troubled south-western province of Balochistan claimed responsibility, according to officials. The Baloch Liberation Army used Twitter to claim the attack, but spokesmen for the group were not available. "They had come to carry out an attack inside the building and take hostages inside," said Omer Ahmed Bukhari, the director general of the Sindh Rangers paramilitary force. He said all attackers were killed within eight minutes. Pakistan's military praised the swift response of the city's security forces in Monday's attack, while the Karachi police released a video of one member of a provincial security unit describing the firefight. "I shot one of them dead... The second guy saw me and... he took out a grenade. I shot him twice in his hand and his weapon fell down. I then shot him in the head as he tried to pull out the grenade pin," said Mohammad Rafiq, a member of an elite rapid response team. The video of the officer was shared widely online, with social media users calling Rafiq a hero. Last year, the US State Department designated the BLA as a global terrorist group, making it a crime for anyone in the United States to assist the militants and freezing any US assets they may have. Following Monday's attack, Pakistani authorities vowed to strike back against any group found responsible, promising to dismantle their networks and destroy their bases. "An investigation has been launched and very soon we will reach their masterminds," Interior Minister Ijaz Ahmad Shah said in a video message. The gunmen never made it into the stock exchange and business continued as usual after the attack.