Concepcion, Chile ? A father’s unanswered cry for his missing son rang out Saturday from the wreckage of a fallen 15-story apartment building that has become a symbol of Chile’s devastating earthquake.

“Jose Luis! Jose Luis!” cried the man, Jose Leon, peering into holes in the concrete that had been carefully cut by rescuers who used body-sniffing dogs to help recover victims.

Emergency workers said Saturday that there is no hope of finding more survivors in the building, and that continuing aftershocks have made the rubble too unstable for firefighters to continue looking for 21-year-old Jose Luis Leon, the only known remaining victim not recovered. Shortly afterward, a huge yellow excavator began clawing into the concrete slabs and twisted metal to completely demolish the structure.

“The family understands that there is nothing else the firefighters can do,” Cmdr. Juan Carlos Subercaseaux told Chile’s Radio Cooperativa, suggesting that the son’s body might be recoverable for burial once the demolition is done.

At least seven significant aftershocks shook Chile on Saturday, the largest with a preliminary magnitude of 5.1, according to the U.S. Geological Survey.

No additional damage or injuries were immediately reported, but aftershocks have dangerously weakened buildings all across the disaster zone, including a 22-story office tower whose now-exposed upper floors have partly pancacked and threaten to crash down onto downtown Concepcion. The city’s mayor has announced at least five contracts for controlled demolitions of such buildings.

At least 500,000 homes were destroyed, but the figure could reach 1.5 million once surveys are complete, Housing Minister Patricia Poblete said.