Rescue workers scoured twisted concrete and rubble into the early hours after a six-storey building in central Madrid collapsed on Tuesday, killing four people and leaving the neighborhood shaken. Emergency services said the collapse occurred shortly before dawn; a municipal emergency spokesperson told reporters crews had "recovered four deceased and were treating several people with injuries" as search operations drew to a close.

The building belongs to RSR, a Saudi-based real estate fund that has invested heavily in high-end hotels and tourist apartments across Spain and Portugal. RSR issued a brief statement expressing condolences to the victims' families and saying it was cooperating with authorities. "We are deeply saddened by this tragedy and are assisting local authorities as they investigate the cause," the statement said.

Madrid's municipal government said the prosecutor's office had opened a preliminary inquiry and that structural engineers and the fire department were examining the site for signs of material failure, renovation work or other causes. "We must determine whether this was an unforeseeable collapse or the result of neglect or improper works," a municipal official said. Authorities have cordoned off neighboring buildings and ordered inspections of adjacent structures.

The collapse will intensify scrutiny of Spain's urban housing stock, which includes both older residential blocks and conversions to tourist accommodation that have been attractive to foreign investors in recent years. RSR and other funds accelerated purchases after the pandemic downturn, betting on a rebounding tourism sector. While companies and city officials have credited the investments with modernizing properties and boosting tourism revenues, incidents like Tuesday's highlight the risks posed by aging infrastructure, complex ownership structures and rapid conversion of buildings to short-term rentals and hotels.

Economists warned of potential market ripples. "A high-profile structural failure in central Madrid is likely to prompt more rigorous inspections and could raise costs for owners, insurers, and tenants," said Ana Reyes, a Madrid-based real estate analyst. She noted that increased regulatory scrutiny and higher insurance premiums would be the most immediate economic consequences, potentially slowing transactions in the most affected neighborhoods.

Insurers and lenders will be closely watching the investigation. Liability claims from victims' families, costs for emergency response and demolition, and potential restoration work could amount to millions of euros for property owners and their underwriters. For funds like RSR, which market portfolios to institutional investors, such an event could lead to reputational damage and demands for greater transparency on maintenance records and compliance with local construction codes.

Local residents and business owners described a scene of shock and mourning. "We heard a huge noise and then the whole street was full of dust," said one shopkeeper across from the site. Madrid's mayoral office said it would accelerate a citywide review of buildings used for tourism accommodation.

As investigators work to determine the immediate cause, the episode underscores broader tensions at the intersection of heritage cityscapes, tourism-driven investment and public safety — and it raises urgent questions about who is responsible for ensuring that foreign capital does not outpace the maintenance and regulation essential to urban life.