"Sixty people were admitted to the city hospital with various injuries, including 11 military personnel," the regional administration said.
The Kazakh Defence Ministry said that the blast was caused by a fire near one of the military unit's warehouses.
Earlier in the day, the ministry said that the explosion had resulted from a fire at a warehouse of a military unit.
"At approximately 19:00 [13:00 GMT], a fire broke out near a warehouse of a military unit stationed in the Jambyl region's Bayzak district. As a result of the fire, unidentified objects exploded," the Kazakh Defence Ministry said in a statement.
Fire brigades continue the effort to eliminate the fire, causes of the incident are being established. The defence ministry also sent a commission headed by Deputy Defence Minister Ruslan Shpekbaev to the scene.
A video of the explosion emerged online.
Residents of houses located close to the military unit in Kazakhstan's south where an explosion was registered will be evacuated, Shpekbaev said.
"This warehouse mostly stores engineering ammunition, which do not have a long range. In order to ensure the safety of the population, measures were taken to evacuate residents of nearby houses," Shpekbaev said in a video address.