The accident took place at approximately 5.30am (same time in Singapore) at a residential building in Wafangdian, which is under the jurisdiction of Dalian City, Xinhua reported.
The fire has been extinguished, and the search and rescue work has been completed. All the injured were sent to the hospital.
The cause of the blast is being investigated.
This is the second such explosion in a week.
On October 21, four people were killed and 47 others injured in a gas explosion at a restaurant in Shenyang, the capital of north-eastern China's Liaoning province.
Video footage shared online shows the massive destruction of a three-story building, with debris littered across the area and nearby buildings affected. Cars parked near the restaurant were also damaged.