The explosion, which took place in a building on Toledo Street, caused widespread damage, according to video footage posted by the emergency information service of Madrid City Hall, Emergencias Madrid.
At least four floors were impacted by the explosion and firefighters are evacuating people from the building, the service said.
“Several people are being treated (for injuries) of various severities,” Madrid Mayor José Luis Martínez Almeida told reporters. One was sent to the hospital, he added.
Martínez-Almeida asked for caution, as authorities are still getting more details after the explosion. “It looks like there was a gas explosion,” he said.
Police officers are at the scene, a Spanish National Police spokesman told CNN.
No one was injured in a nearby elderly home and all residents were evacuated, the mayor said. The director of the Los Nogales residence, Antonio Berlanga, confirmed this report.
This is breaking news and will be updated.