Police in the English city of Birmingham declared a "major incident" after reports that a number of people were injured in stabbings early on Sunday, with the cause of the incidents as yet unclear.
Britain's Foreign Secretary Dominic Raab said he had no information to indicate the incidents were terrorism related but the public should stay "very vigilant".
West Midlands Police were called to reports of a stabbing in Birmingham city centre at approximately 12:30 a.m.
"A number of other stabbings were reported in the area shortly after," they said in a statement.
"We are aware of a number of injured people, but at the moment we are not in a position to say how many or how serious."
Emergency services worked at the scene to ensure those who were injured received medical care, police said.
Police cordons were in place on Sunday morning in three separate locations in the city centre: Hurst Street, Irving Street and Edmund Street.
A knife was visible to a Reuters witness beside a drain in Edmund Street.
West Midlands Mayor Andy Street said the series of incidents in the Hurst Street area of the city centre appeared to be related but the motivation for them was not yet understood.
"At this early stage it would not be appropriate to speculate on the causes of the incident," the police said.
A witness told the BBC she saw "multiple people having fist fights".
The BBC said the cordon in Hurst Street was near the area known as the Gay Village in the centre of Birmingham, where many people had been seated at outdoor tables eating and drinking.