(CNN) -- A blast at a tax office that left four dead and 19 injured in central China was a deliberate attack, state media reported Saturday.
The explosion Friday struck a local tax office near a downtown residential block in Changsha city, Xinhua news agency reported.
It left the third-floor windows shattered. A preliminary probe shows the Friday attack was planned, police said.
An investigation is underway.
A separate series of explosions at a barbershop in northeast China killed one person and injured 20, Xinhua said.
The barbershop attacks were in Jilin province.