Lancashire Police officers were filmed using what appeared to be pepper spray at Deepdale this afternoon, saying some "aggressive" fans tried to "forcibly exit" PNE's stadium - but what exactly is pepper spray?
Also known as PAVA spray, it is used by police via handheld cans that can reach up to four metres.
It isn't lethal, but is noxious enough to cause an intense, temporary debilitating burning sensation that incapacitates its victim.
Although used in other countries, such as America, as a self-defence weapon, it is banned here, except for use by law enforcement.
It is outlawed under section five of the Firearms Act 1968 as a "weapon of whatever description designed or adapted for the discharge of any noxious liquid, gas, or other thing."
Previously, the police used tear gas, or CS gas, but PAVA - is said to be much more potent, with the pain to eyes reported to be much greater.
Although there have been times where PAVA and CS have failed to work, especially when the victim is drunk or on drugs, the effectiveness rating is still very high.
Recovery takes between 15 and 35 minutes.
It is usually used to disarm a suspect or to control crowds, such as during riots or other public disorders.