A natural gas leak was the apparent cause of Friday’s blast at Havana’s 96-room Hotel Saratoga. The 19th-century structure in the city’s Old Havana neighborhood did not have any guests at the time because it was undergoing renovations ahead of a planned Tuesday reopening.

Relatives of missing people remained at the site late Friday night as rescuers sifted through rubble. Others gathered at hospitals where the injured were being treated.

“I don’t want to move from here,” Cristina Avellar told The Associated Press near the hotel, whose outer walls were blown away by the explosion, leaving the interiors of many rooms exposed.

Avellar was waiting for news of Odalys Barrera, a 57-year-old cashier who has worked at the hotel for five years. She is the godmother of Barrera’s daughters and considers her like a sister.

Although no tourists were reported injured, the explosion is the latest blow to the country’s crucial tourism industry.

Even before the coronavirus pandemic kept tourists away from Cuba, the country was already struggling with the sanctions imposed by former US President Donald Trump and 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 hotel’s first floors appeared to have suffered most of the damage from Friday's blast. The missing walls made it possible to distinguish mattresses, pieces of furniture, hanging glass, tattered curtains and cushions covered in dust.

Dr. Julio Guerra Izquierdo, chief of hospital services at the Ministry of Health, said at least 74 people had been injured. Among them were 14 children, according to a tweet from the office of President Miguel Díaz-Canel.

Cuba’s national health minister, José Ángel Portal, told The Associated Press the number of injured could rise as the search continues. Fire Department Lt. Col. Noel Silva said rescue workers were still looking for a large group of people who may be under the rubble.

The search continued through the night. The shattered hotel remained cordoned off as workers operated heavy machinery to lift huge pieces of wall and masonry and trucks left the site loaded with rubble. Firefighters and rescue workers toiled inside the wreckage.

Authorities refused to release the names of the dead, even to their relatives. Authorities placed emergency lights at the site and brought in trained dogs to help in the search.

Rescuers declined to answer questions because the authorities had ordered them not to avoid confusion.

A 300-student school next to the hotel was evacuated. Havana Governor Reinaldo García Zapata said five of the students suffered minor injuries.

The emblematic hotel is about 100 meters from Cuba’s Capitol building, which had broken glass and damaged masonry after the explosion.

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. The company said it was investigating the cause of the blast.

In the past, the Hotel Saratoga has been used by visiting VIPs and political figures. Beyoncé and Jay-Z stayed there in 2013.