The explosion occurred at 2 p.M. At Xinmin Town, Fugu County, in Shaanxi Province.
Initial investigation indicates that the makeshift house had been built inside a residential compound.
It remains unclear what caused the explosion, state-run Xinhua news agency reported.
The township's hospital was among the buildings destroyed or damaged by the blast, reporters at the scene confirmed.
Dozens of firefighters and rescuers are combing the rubble for more survivors.
So far 94 people had been admitted to hospital, including four who are in intensive care.