A gas leak is thought to be the cause of the explosion at Hotel Saratoga, according to the Cuban Presidential Office, who said that more details would follow.
“Everything indicates that the explosion was caused by an accident,” the Cuban Presidential Office said in a tweet.
According to preliminary data, a child and a pregnant woman were among those who died, it said.
The presidency also said 64 people have been hospitalized for injuries, including 14 minors.
Cuban state TV said there are potential survivors trapped in the basement of the destroyed hotel.
Witnesses described a “massive blast,” which appeared to destroy buses and cars outside the hotel in the center of the city.
Images from the scene showed the blown-out facade of at least three floors of the ornate green-and-white stuccoed building. Plumes of dust and smoke could be seen rising around debris on the ground.
A CNN team on the ground saw a bloodied woman being carried away at the scene of the explosion. Fireman were using their bare hands to move chunks of broken granite and stone in order to pull people out of the rubble. Pieces of metal awnings, balconies and large chunks of stone were scattered about 300 feet away from the hotel.
Cuban President President Miguel Diaz-Canel visited the site of the explosion on Friday and Hermanos Ameijeras hospital, where a number of victims were sent to, according to images shared by the Presidential Office on Twitter.
He said the explosion was “not a bomb nor an attack, it’s a regrettable accident,” after returning to the site of the blast.
Hospitals continue to treat all the wounded and rescue activities are still underway, he added.
Mexico’s foreign minister tweeted his solidarity with explosion’s victims. “Our solidarity to the victims and those affected as well as the people of that dear fraternal nation,” Marcelo Ebrard said in a tweet.