According to preliminary information, the explosion was caused by a cylinder leak inside a house.
The blast brought the structure down, trapping several people under the debris.
Rescue workers acted swiftly and have so far pulled 15 people from the rubble.
Ten of the injured were shifted to nearby hospitals, with officials saying the condition of some remains critical.
Additional Deputy Commissioner Sahibzada Yousaf reached the scene after the incident and supervised the rescue efforts.
He said rescue teams were making every possible effort to locate and recover anyone still trapped beneath the debris.
He confirmed that 15 people had been rescued so far and said the search operation would continue.
Residents of the area said the sound of the explosion was heard from far away.
After the blast, police cordoned off the area, while gas and electricity supplies were temporarily suspended to prevent any further accidents.
Authorities said a full investigation would be conducted to determine the exact cause of the explosion and to take necessary measures to prevent similar incidents in the future.