A “number of individuals” were involved in a fight with weapons which police are linking to a stabbing hours earlier.
In the first attack, a man in his 40s was wounded in the back near Raza Jamia mosque in Lower Antley Street, Accrington, shortly after 14:30 BST on Friday.
Less than three hours later a group began fighting a few roads away in Steiner Street while, at about the same time, an assault took place half a mile south in Craven Street.
A man who was stabbed in the neck during one of the later incidents was taken to hospital where he is described as “very poorly”. The man injured in the first attack remains in a “serious but stable” condition.