Anti-terrorism officers were helping to investigate a knife attack in a northern English town on Saturday in which one man was injured, although police said they were keeping an open mind.
A woman was arrested, they said, after what officers earlier called a "serious incident" in Barnsley which resulted in the man suffering minor injuries.
A kitchen knife had been recovered and was being forensically examined, South Yorkshire police said.
"At this stage we are keeping an open mind as to the motivation ... we are receiving support from detectives at Counter Terrorism Policing North East. It is not appropriate to speculate further," the police said in a statement.
An investigation had begun to establish whether it was an isolated incident and whether the suspect acted alone.
Sections of the town centre shopping area where the incident occurred were still cordoned off on Saturday as forensics officers clad in white suits gathered evidence.
Police have released no further details of the incident, but urged the public to remain vigilant and appealed for witnesses.
"We understand that this morning's incident will have been distressing and shocking for those in the town centre ..," said Assistant Chief Constable Tim Forbes.
"Rest assured we are working relentlessly to piece together what happened," he added.