Two people have died and at least 18 were injured in a strong explosion that rocked a four-storey building being renovated in central Madrid, Spanish authorities say.
Two men working on the building died in the explosion, Madrid's Mayor Jose Luis Martinez-Almeida said on Friday evening.
Of the 18 people hurt, most of the injuries were not serious, officials said.
Earlier, he said four people had been taken to hospital, one in serious condition, adding the cause of the blast was not yet clear.
"Some kind of works were being done in the building" in the upmarket Salamanca neighbourhood where the explosion occurred, he said.
"Firefighters are inside checking the building's structure and to determine whether more people could be inside," he told Telemadrid TV channel.
Emergency service spokeswoman Gema Martin said that a school across the road from the building was not damaged and that there was no need to relocate the children.