The blast on Monday shook the commercial area of San Cristobal, less than 30 kilometers (18 miles) from the capital Santo Domingo, sparking a fire that burned for hours, and a huge column of smoke.
The official, Delfin Antonio Rodriguez told local news channel SIN that there were 25 victims who had either died at the scene, or later in hospital.
An official death toll will be announced later in the day.
Of the 59 people injured, 37 remained hospitalized, emergency officials said.
Local media reported that some of the wounded had suffered burns on up to 40 percent of their bodies.
Authorities said Monday that a four-month-old baby was among the dead.
The cause of the explosion has not been determined, nor has its exact origin.
The blast and resulting fire affected nine buildings, and partially destroyed four.