Police are at the scene of a major incident in Colne Road, Burnley.
Officers were called shortly after 9pm to reports shots had been fired at a property on the street.
A Lancashire Police spokesman said: "Officers remain at the scene and an investigation is in its early stages to identify those involved. Damage has been caused to a window, however there are no reports of any injuries.
"Anyone with information should call 101 quoting log number 1411 of 13th October. Alternatively independent charity Crimestoppers can be reached anonymously on 0800 555111 or online at socsi.in/aYSa1."