A spokesman for the Pakistan Rangers told reporters that three of the slain terrorists have been identified as Umarzada, Khalil and Haider who were killed in Mangopir area.
"They were planning to carry out terrorist attacks in the city on a large scale. They were killed in a gunfire battle with the rangers," he said.
A Rangers soldier was also injured in the gunfire.
The spokesman said operations against terrorist outfits in Karachi had been stepped up after the Tehreek-e-Taliban Pakistan's attack on the Army Public School in Peshawar on yesterday in which 148 people, mostly schoolchildren, were killed.