The 57-year-old was arrested at the scene after being stopped by members of the public following the incident in December.
The suspect was detained on December 3rd for 28 days under Section 2 of the act for an assessment of his mental health.
However, Lancashire Police confirmed to the Burnley Express today that the suspect continues to be detained.
Two women attacked in the St James' Street store suffered serious but not life-threatening injuries.
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An employee in her 40s and a shopper in her 60s were taken to hospital.