Ambulance has tyres slashed while treating critically ill patient

A man has been arrested after an ambulance had its tyres slashed while paramedics worked to save a critically injured pedestrian.

Police had to use CS spray to subdue the man who was wielding a knife.

It happened at just before midnight last night in Greenford, west London.

The pedestrian, a man in his 20s, remains in critical condition after being taken to hospital.