The Clutha Vault pub has been "totally devastated" by the helicopter crash which may have killed up to nine people.
Scottish Fire and Rescue Service assistant chief officer David Goodhew said parts of the building were "unrecognisable".
"The building has been totally devastated. It's totally unrecognisable in most parts," Mr Goodhew said.
"There's a large amount of debris that's underneath the helicopter and therefore you have to dig in slowly and methodically."
The bodies of the nine people who died when a police helicopter crashed into a Glasgow pub have been released to their families.
The removal of a helicopter from a Glasgow pub has enabled emergency services to continue their search for victims of Friday's tragedy.
Emergency workers are searching the wreckage of a Glasgow bar a night after a police helicopter crashed through its roof during a concert.