A powerful explosion apparently caused by a natural gas leak has killed at least 18 people and injured dozens more when it blew away a luxury hotel’s outer walls in Cuba’s capital, Havana.

A pregnant woman and a child were among those killed, according to the latest Twitter post by Cuba’s presidency.

“It has not been a bomb or an attack. It is a tragic accident,” President Miguel Díaz-Canel, said in an earlier tweet, after visiting the site.

No tourists were staying at Havana’s 96-room Hotel Saratoga because it was undergoing renovations.

Cuban state TV reported the blast was caused by a truck that had been supplying natural gas to the hotel, but did not provide details on how the natural gas ignited.

Cuba’s national health minister, José Ángel Portal, told The Associated Press that hospitals had received about 40 injured people.

But he said the number of injured could rise as the search continues for people who may be trapped in the rubble of the 19th century structure in the Old Havana neighbourhood of the city.

Local officials said 13 people were missing while a school next to the hotel was evacuated and news media said no children were hurt.

Worried relatives of people who had been working at the hotel showed up at a hospital in the afternoon to look for them. Among them was Beatriz Céspedes Cobas, who was 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.

Police cordoned off the area as firefighters and rescue workers toiled inside the wreckage of the emblematic hotel about 100 metres from Cuba’s Capitol building.

Cuba is struggling to revive its key tourism sector which has been devastated by the coronavirus pandemic.

The Hotel Saratoga has been used frequently by visiting VIPs and political figures, including high-ranking US government delegations. Beyoncé and Jay Z stayed there during a 2013 visit to Cuba.

Besides the pandemic’s impact on Cuba’s tourism, the country was already struggling with the sanctions imposed by the former US President Donald Trump that have been kept in place the 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 somewhat early this year, but the war in Ukraine crimped a boom 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 iconic beach town of Varadero,  aimed at drawing investors.

By ANDREA RODRÍGUEZ (Associated Press) in Havana