The "bomb" looks like a Soviet/Russian/Chinese 82mm mortar round. The police Explosive Ordnance Disposal Bureau would definitely turn up to an incident like this so strange you didn't see them.
I must have missed them. The last time I saw them was around the Tai Tam / Wong Nai Chung area and I do recall they travel around in specialist vans / trucks.
According to the news article linked above, they were called.
About 15 mins before I went for my coffee run, I spotted this on our street... when I saw the cops while coming back, my first reaction was "someone tried steal or drive and crashed a Pagani Zonda".
Waaay too much excitement for one morning.
The Pagani Dealership is right around the corner... you can see zondas there quite often lol