Police and ambulance services were called out to Fishergate after an elderly man suffered a serious "medical episode", say ambulance services.
A man who ambulance services say is in his mid-seventies collapsed at around 12.30pm on Tuesday, January, 9 near to the Cotswold shop at the junction of Cheapside.
A spokesman for the ambulance service said: "We were called out via a 999 call to reports that an elderly man had collapsed.
"The man is believed to be in a life-threatening condition and the hospital were notified in advance that the patient was on his way."
The man was taken to Royal Preston Hospital by ambulance.