A powerful explosion apparently caused by a natural gas leak killed at least nine people and injured 40 on Friday, when it blew away outer walls from a luxury hotel in the heart of Cuba’s capital.

No tourists were staying at the 96-room Hotel Saratoga because it was undergoing renovations, Havana governor Reinaldo Garcia Zapata told the Communist Party newspaper Granma.

“It has not been a bomb or an attack. It is a tragic accident,” president Miguel Diaz-Canel, who visited the site, said in a tweet.

The blast sent smoke billowing into the air around the hotel with people on the street staring in horror and cars honking their horns as they sped away from the scene, video showed.

The blast came as Cuba struggles to revive its key tourism sector, which was devastated by the coronavirus pandemic.

Cuba’s national health minister, Jose Angel Portal, told The Associated Press that hospitals had received about 40 injured people, but said the number could rise as the search continues for people who may be trapped in the rubble of the 19th century building in the Old Havana neighbourhood.

Granma reported that officials said 13 people were missing. A school next to the hotel was evacuated and news media said no children were hurt.

Police cordoned off the area as firefighters and rescue workers worked inside the wreckage of the hotel,  about 100 metre from Cuba’s Capitol building.

The hotel was first renovated in 2005 as part of the Cuban government’s revival of Old Havana and is owned by the Cuban military’s tourism business arm, Grupo de Turismo Gaviota SA.

It has been used frequently by visiting VIPs and political figures, including high-ranking US government delegations. The Mexican newspaper Excelsior reported that Beyonce and Jay Z had stayed there.

Photographer Michel Figueroa said he was walking past the hotel when “the explosion threw me to the ground, and my head still hurts – everything was very fast”.

Worried relatives of people who had been working at the hotel arrived at a nearby hospital to look for them. Among them was Beatriz Cespedes Cobas, who was tearfully searching for her sister.

“She had to work today. She is a housekeeper,” she said. “I work two blocks away. I felt the noise, and at first, I didn’t even associate”, the explosion with the hotel.

Yazira de la Caridad said the explosion shook her home a block from the hotel: “The whole building moved. I thought it was an earthquake.”

“I’ve still got my heart in my hand,” she said.

Besides the pandemic’s impact on Cuba’s tourism sector, the country was struggling with the sanctions imposed by the former US president Donald Trump that have been kept in place by the Joe Biden administration.

The sanctions limited visits by US tourists to the islands and restricted remittances from Cubans in the US to their families in Cuba.

Tourism had started to revive early this year, but the war in Ukraine cut the number of Russian visitors, who accounted for almost a third of the tourists arriving in Cuba last year.

The explosion happened as Cuba’s government hosted the final day of a tourism convention in the beach town of Varadero aimed at drawing investors.

Mayiee Perez said she went to the hotel after receiving a call from her husband, Daniel Serra, who works at a foreign exchange shop inside the hotel.

She said he told her “I am fine, I am fine, they got us out”, but she was unable to reach him after that.