Employees inside holed up in locked rooms or were evacuated out a back entrance. Authorities found other arms and food items with the gunmen, who were killed in a battle with security forces that lasted about 12 minutes.
Khattab said that RAW orchestrated the entire thing: it planned, funded and ordered the PSX attack for the BLA to carry out. The group has been waging an urgency for years, demanding independence for Pakistan's gas-rich southwestern Baluchistan province, which borders the southern Sindh province, where Karachi is the provincial capital.
The gunmen initially threw a grenade then opened fire on a security post outside the building.
The attackers were not able to enter the main compound, Farrukh Khan, chief executive officer of the exchange said by phone.
Besides the four security guards, a police officer and an investor were among those killed in the attack, the police said.
Director General Rangers Sindh Major-General Omer Ahmed Bokhari, addressing a press conference in Karachi, said the attackers meant to not only enter the building but also carry out violence and hold people hostage.
The Pakistan Stock Exchange administration sent out a message saying that "rangers" had entered the compound and that "four terrorists" were dead. "We were all terrified", said Abid Habib, PSX's director "There was gunfire and suddenly everyone was rushing to the windows to see what was happening".
Images from the scene show the bodies of a number of men on the ground next to large amounts of ammunition and weapons.
Militant groups however still retain the ability to launch periodic attacks in many rurals areas of the country. The stock exchange is located at one end of I.I. Chundrigarh Road, home to the central bank, and headquarters of most major banks in the nation.
MapWhy are Baloch groups fighting?
Reports said the Baloch Liberation Army has claimed responsibility of the attack.
In a strongly-worded response, External Affairs Ministry Spokesperson Anurag Srivastava said unlike Pakistan, India has no hesitation in condemning terrorism anywhere in the world, including in Karachi. All staff inside the building were unharmed.
Previous year the BLA attacked a five-star hotel in the port city of Gwadar in Balochistan. The group is banned in Pakistan, the United Kingdom and the US.
Balochistan is a sparsely populated region, and the BLA and other militants have sanctuaries there and in adjoining areas in Pakistan.