At least two people were injured when scaffolding on a huge building collapsed.
Fire crews are using thermal imaging to search the massive piles of wood and metal for more victims.
The emergency services received multiple calls from witnesses at the scene at Greyfriars House in Reading at 11.15am.
One of the victims is suffering from chest pains and another for a head injury, their conditions are not yet known, Mirror Online reports.
One witness reported hearing "lots of shouting and running away after a sudden crash" while another "thought it was a low flying plane."
An ambulance service spokesman said: "We received multiple calls from members of the public at 11.15.
"We have got staff there treating two patients.
"One has chest pains and one has a head injury."
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