Police have arrested the driver and seized the truck while Army has also initiated an inquiry into the matter.
According to the police, an Army truck was passing through Sabzi Mandi in Paota when its driver lost control over it and the vehicle steered into the crowd.
Suresh Dadheech died on the spot and Shahnaz Bano succumbed to her injuries at MDM hospital, police said.
The truck stopped after hitting a bus.
Shahnaz's son was also injured in the accident.
Army has expressed grief over the accident and has ordered an inquiry into the matter.
"We have ordered an inquiry into the matter and the engineers of the Army will check the truck to find out the exact cause of the accident and verify the statement of the driver," said Defence spokesman Col S D Goswami.