Multiple people are feared trapped in rubble after a devastating blast ripped through a 4-storey building in central Madrid.
What's believed to be a gas explosion tore through three floors of the building in the upmarket area of Salamanca, leaving at least 17 people with injuries.
According to local news outlet Levante, firefighters have evacuated one person from the building, where several more people are believed to be trapped.
Madrid's official Emergency Information Twitter account has confirmed in a tweet that medics have treated 17 people with injuries. Of these 17 people, 4 have been transferred to hospitals, one with serious injuries.
Meanwhile, footage has emerged showing police deploying drones to scour the ruins for victims and survey the state of the building from the air.
According to a tweet from the Emergency Information feed, two building operators remain missing in the wake of the horror blast.
Firefighters are reportedly working inside the building while the Servicio de Asistencia Municipal de Urgencia y Rescate - Spain's specialised emergency unit, work to treat the injured.
The explosion appears to have completely destroyed the facade of the building, in which Madrid Mayor Jose Luis Martinez-Almeida said "some kind of works were being done" where the explosion took place.
"Firefighters are inside checking the building's structure and to determine whether more people could be inside," he told Telemadrid TV channel.
The cause of the explosion was not yet clear, he said.
The Nuestra Señora de Loreto del Pilar school, located close to where the explosion took place, has not been affected. Children who were in the courtyard had reportedly been frightened by the noise and stones that had fallen in the courtyard.
A witness to the explosion told local news outlet El Periódico de España of how they were right next door when the blast occurred.
"Everything exploded, we got out as soon as possible," they said.
The witness, who had not been named, said they helped to get the injured parties out of the building.
Another young woman who had seen the explosion said it appeared to have come from below.
"A huge smoke has been mounted and it has come out like a circular smoke, like a mushroom," she said.
A spokesman for the regional government-run emergency coordination centre said in a tweet: “There has been an explosion in Ayala Street.
“Firefighters, paramedics and police are working in the area. Avoid the area to facilitate the movement of vehicles."
Footage from the scene posted to Twitter pans around streets shrouded by smoke.
Pieces of debris including wood, bricks and what appears to be shattered glass, line the roads and footpaths around the building.
As the camera pans upwards, more grey smoke can be seen rising from a four-storey building, which has what appears to be a store on the street level.
Another piece of footage shared online shows a street leading to the site of the explosion, which is obscured by a thick cloud of smoke.
Frightened pedestrians are seen fleeing the scene while two women are seen runing towards the smoke.
"Gas explosion in the Salamanca district," the video is captioned.
"Firefighters on site."
In January last year an explosion occurred in a building in Madrid which caused it to partially collapse.
It killed four people and wounded ten others.
