The death toll from a devastating apartment fire in the eastern Spanish city of Valencia has risen to 10, officials said Friday. Initially, the death toll stood at four with up to 15 people missing.

"We can confirm that following a first inspection, forensic police have found 10 fatalities," regional administrator Pilar Bernabe told reporters.

Spanish Prime Minister Pedro Sanchez on Friday traveled to Valencia to see the damage firsthand and to meet with local officials. 

Speaking with reporters, Sanchez said residents had, "lost everything in a matter of minutes in this terrible fire."

Authorities investigating cause of fire

The blaze began on Thursday evening for as yet unknown reasons on the fourth floor of the 138-unit, 14-story apartment complex and immediately spread, accelerated by high winds.

Esther Puchades, the head of Valencia's Industrial Engineers' Association, confirmed that the building's cladding included polyurethane, and that this likely contributed to the acceleration of the fire.

However, the association for the polyurethane industry said in a statement that no polyurethane was used in the building's facade.

Observers were quick to draw parallels to London's 2017, Grenfell Tower blaze, which was traced back to the use of highly flammable facade elements and led to the death of 72 residents.

Now, only a skeleton of the former Valencia structure remains as firefighters and engineers seek to determine whether the complex will have to be razed due to structural damage the building may have suffered from extended high temperatures.

Firefighters on Friday battled falling debris and damaged infrastructure as they continued to look for survivors and identify the charred remains of victims. Officials say there is little hope of finding anyone alive inside the building.

A local magistrate has already announced an investigation into the incident.

Three days of mourning have been declared in Valencia, with soccer matches and local festivals all canceled or delayed.

Mayor Maria Jose Catala said that 131 temporary residences were being prepared for those made homeless by the fire, with city residents generously donating clothes, medicine and toys for victims.

js/nm (AFP, dpa, Reuters)