On my way home tonight there was a police cordon on Robson Street just below Thurlow (1 block from my apartment). There was a large number of police officers (6+ cars worth), along with 2 ambulances, a stopped Robson city bus, and a ton of curious onlookers.
The policeman I asked wouldn't give me any information about what had happened. The only info I got came from onlookers, who said that somebody had gotten stabbed (possibly had their throat slit). 2 different stories were going around: that a bus driver had been stabbed, or that it was a homeless guy that got stabbed.
I walked by a little after 9 PM. The police were fully set up by then, so I imagine the action took place some time before then.