MADRID, SPAIN: Two people were reported missing after an explosion in the heart of Madrid, according to local emergency services, who also indicated that 18 people were injured.

According to reports, the explosion happened at number 35 Calle Ayala in the upscale Salamanca neighbourhood in the centre of the Spanish capital at around 1.30 p.m. on Friday. The explosion appears to have been caused by a gas leak, though this is still being investigated.

"Fatalities cannot be ruled out," Madrid Mayor Jose Luis Almeida told reporters on Friday evening. Meanwhile, Rafael Ferrandiz, the head of the Madrid Fire Department, reported that the two workmen who went missing were believed to be on the third floor of a building when the explosion happened.

According to Ferrandiz, the workers could have tumbled down to the bottom floor patio, which had been buried by two metres of solid rubble. To find the workers, firefighters are using dogs and drones. 

The explosion has rendered the structure "extremely unstable," with "a risk of collapse,"  Therefore, , urgent work is being done to stabilise the structure, Ferrandiz said.  An 84-year-old male was rushed to intensive care in a "extremely serious" condition, along with a 77-year-old lady who suffered multiple brain injuries and a 44-year-old woman who suffered leg injuries.

Blast in Pakistan's southwest Quetta, Several injured

Explosion in new EV scooter at midnight, 1 died and 3 injured

US envoy warns, North Korea could stage nuclear test this month