PeckTech

I'd say the reason is they have five times more officers on duty than usual and are almost certainly short on transport and time. Doesn't seem very clever to have hundreds of officers sitting at traffic lights. Anyway, my point was it could be anything and not to get unduly alarmed, as they say.

Pretty sure they'll be relaxing that siren rule this week...

Lots of officers coming on for the night shift around this time - could just be moving resources around. 16,000 police need a lot of transport, so the sirens go on to save time.