British police said on Saturday they were responding to a serious incident in the northern English town of Barnsley.
"There is a high visibility police presence in Barnsley town centre this morning ... responding to a serious incident. More information will follow," South Yorkshire police said. "Public are asked to be vigilant."
Unconfirmed social media reports said that a woman had been arrested after several stabbings at a market in the town and that police were searching for possible accomplices.
No further details were immediately available.