Firefighters were searching on Tuesday through smouldering rubble as people gathered outside hospitals, looking for missing loved ones.
President Luis Abinader visited San Cristobal, located just west of Sango Domingo, to meet with those affected, saying an additional 11 people were missing and that authorities were still trying to extinguish the fire amid collapsed buildings and charred vehicles.
"We're doing everything humanly possible ... to investigate the situation of the 11 missing," he said.
"The search for survivors has been very difficult."
Monday's explosion also left more than 50 people injured as the blast tore through a bustling commercial centre in San Cristobal, authorities said. At least 36 of the injured remained in hospital, said Joel Santos, minister of the presidency.
Health Minister Daniel Rivera said authorities have still not been able to access "ground zero" where the explosion occurred because the site was still burning.
The country's emergency telephone system said the explosion occurred at a bakery in the city's centre, a bustling area known as Old Marketplace. The fire then spread to a hardware store next door and a nearby furniture store.
More than 500 first responders and officials responded to the explosion, which destroyed four buildings and damaged nine others, Juan Manuel Méndez, director of the Emergency Operations Center, told reporters.
Among the victims was a four-month-old baby who died from head trauma and a woman who worked at a bank, officials said.
Smoke still engulfed the city centre on Tuesday, and Rivera urged everyone to wear face masks.
"This smoke is mixed with chemicals," he warned.
Rivera said he and other officials will go door to door to ensure that people have masks and determine whether they had any respiratory or skin problems. He also was expected to visit patients at a local hospital, where people were still searching for loved ones.
"The first 24 hours are very important," he said, adding that injuries included burns, fractures and respiratory problems.
Abinader said the government would set up two mobile hospitals to provide further treatment, including psychological services to those affected.
Meanwhile, Santos said the government is launching an investigation to determine whether the business where the explosion occurred was operating under proper regulations.
It wasn't clear what caused the explosion, and authorities have not provided a preliminary estimate of damages.
"These catastrophes have an order of priority: save lives, save assets, ensure that the incident is extinguished and then assess damage," Santos said at a news conference.
San Cristobal, the birthplace of dictator Rafael Trujillo, was the site of another explosion nearly 23 years ago. An arms depot exploded in October 2000, killing at least two people and injured more than two dozen others, forcing authorities to evacuate thousands.