Two male police officers are being treated in hospital after they were stabbed by a man near Leicester Square in central London.
The Metropolitan Police said a Taser was used in the incident at around 6 a.m. and a man was arrested on suspicion of bodily harm and assaulting an emergency worker.
The status of the two officers is not known and their families are also aware of the incident, which is not considered terrorism-related.
The arrested man was taken to hospital for treatment, where he remains at this time.
Footage from the scene showed officers guarding an area of Whitcomb Street that had been cut off.
A spokesman for London Ambulance Service said the service was called to reports of an incident on Great Windmill Street, near Shaftsbury Avenue at 6:01am.
They added that three ambulances, a response vehicle ambulance and a London air ambulance were dispatched to the scene and three people were treated and taken to hospital.
Mayor of London Sadiq Khan condemned the attack and urged anyone with information about the incident to contact police.
He described it as “absolutely appalling”, adding that officers “are doing their duty and supporting the public at this critical time for our country”.
“My thoughts and prayers are with them, their loved ones and police colleagues following this shameful attack.
“Assaults against police will not be tolerated and any perpetrators will be arrested and prosecuted,” he said.
The mayor added that he has spoken to commissioner Sir Mark Rowley and remains in close contact.
Police said investigations into “the circumstances surrounding the incident are continuing”.