At least six people were injured in an explosion that occurred around 1 p.m. in a building in Madrid's Salamanca neighborhood, the Civil Defense Service reported.

The cause of the incident remains unclear at this time. Spanish media have suggested that it could be a domestic gas explosion or a boiler explosion inside the building.

Rescue services have set up a field hospital near the scene in case more casualties are found.

In the meantime, police have cordoned off the area and firefighters are inspecting the building for other damage.