Armed officers are at the scene of an incident in Clitheroe, say police.
Witnesses around the Lowergate area reported a large police presence with several roads blocked on Wednesday evening.
An ambulance was also present.
Police are currently unable to comment further on the incident, but issued reassurances to the wider public.
A police spokesman said: "There has been a police operation involving armed officers.
"We would like to reassure the general public that the situation is in hand and there is no risk to the wider public.
"A full statement will follow shortly."
It has been confirmed that the incident in no way involves the Key Street bar.