A fire in the Spanish city of Valencia has killed at least 9 people The death toll in a fire that engulfed an apartment block in the Spanish city of Valencia rose Friday to nine. One person remained missing, according to forensic police.

A fire in the Spanish city of Valencia has killed at least 9 people

Firefighters work at a burned block building in Valencia, Spain, on Friday. Alberto Saiz/AP hide caption

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Alberto Saiz/AP

Firefighters work at a burned block building in Valencia, Spain, on Friday.

Alberto Saiz/AP

VALENCIA, Spain — The death toll in a fire that engulfed an apartment block in the Spanish city of Valencia rose Friday to nine as questions were raised about whether construction materials caused the fire to spread so rapidly.

One person remained missing, according to forensic police, who after identification procedures downgraded the death toll from an official's account of 10 provided earlier following a visual count of remains.

The fire started Thursday evening and quickly engulfed the two residential buildings. Neighbors described seeing the rapid spread of the blaze, residents stuck on balconies and hearing children screaming.

"I have no words to describe the suffering of those poor people," said Sara Plaza.

Police found 9 bodies in the gutted residential buildings. Valencia's national government delegate confirmed that the bodies matched the list of people that authorities had been trying to locate and that one person remained missing.

Neighbor Alejandra Alarcón said it took 15 minutes for the fire to engulf an entire building, as questions abounded as to how the fire spread so rapidly.

Experts suggested that a type of cladding might have made the blaze spread faster, but Valencia Mayor María José Catalá said the cause of the fire was still not known and it was too early to comment on whether some materials used in construction of the modern complex might have contributed.

The vice-president of the Valencia College of Industrial and Technical Engineers, Esther Puchades, who once inspected the building, told the state news agency Efe that the cladding used included polyurethane and when "heated it is like plastic and it ignites."

She said it was the first fire of its type in Spain, but that other blazes involving the material have been similarly destructive in the United Kingdom and China.

Spain's polyurethane manufacturers' association, IPUR, issued a statement contesting Puchades' claim, saying there was no evidence that polyurethane was used in the Valencia building's façade.

The June 2017 fire at Grenfell Tower in London, which had similar cladding, caused 72 deaths.

In the Grenfell Tower, the exterior walls of the 25-story public housing complex were covered by a layer of foam insulation topped by what are called aluminum composite material (ACM) rainscreen panels. These are essentially two sheets of aluminum sandwiched around a layer of polyethylene, a combustible plastic polymer that melts and drips on exposure to heat.

A housing block burns in Valencia, Spain, on Thursday. Alberto Saiz/AP hide caption

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Alberto Saiz/AP

A housing block burns in Valencia, Spain, on Thursday.

Alberto Saiz/AP

After a faulty refrigerator started the fire in a fourth floor apartment, the flames quickly spread to the exterior cladding and began climbing up the outside of the building. The fire reached the roof within minutes, then spread to engulf much of the structure, trapping residents in their apartments.

A public inquiry into the fire found that the flames spread rapidly owing to the presence of aluminum composite material and polyethylene, a substance similar to polyurethane.

The complex in Valencia was finished in 2009. In a promotional video, the now bankrupt construction company Fbex boasted that it used a new aluminum-based material as part of its façade.

Fifteen people were treated for injuries and two remained in city hospitals. Both were said to be stable.

Prime Minister Pedro Sánchez visited the scene, promising support for those affected and expressing gratitude to firefighters and military personnel who worked to extinguish the blaze.

Pope Francis also sent a telegram of condolences.

It was not immediately known how many people were in the two buildings when the fire broke out, but dozens are believed to have lost their homes and belongings. The complex had some 140 apartments.

The Valencia regional government declared three days of mourning and announced financial aid to cover accommodation, clothing and food.

Weekend soccer games involving Valencia and Levante have been postponed after both clubs requested not to play in the immediate aftermath of the fire, the Spanish league said.

Residents were housed overnight in hotels or in the homes of relatives and neighbors, authorities said. Neighbors also responded by donating clothes and food in shops for the survivors.

Firefighters rushed to the scene on the outskirts of the city as flames burst from windows. They used a crane to lift two residents from one of the balconies.