Commentator Keli Goff has told Daybreak that "churches around the US will be ringing bells 26 times to commemorate the lives lost in the US shooting."
She added: "There's also going to be a moment of silence across the internet. A number of news sites will actually go dark at 9.30am."
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The former panellist and Oxo mum made a final, moving return to the show earlier this month - in which she received a rapturous response.
The 66-year-old said he decided to stop chemotherapy treatment for her terminal cancer in order to regain control of her life.