Rescue workers periodically turned off all equipment and asked relatives of missing people to call so that they can pinpoint ringing phones, rescue service spokeswoman Viktorija Sembele said.
She said work was proceeding slowly since both the rubble and remaining sections of roof were like a house of cards and could easily collapse further if a wrong piece is moved or lifted.
Firefighters suffered casualties when large sections of roof fell on them right after their arrival on the scene.
