I was ust in Santa Monica 2 months ago and walked up and down the pedestrian mall on third ave (I think it's third). Is that where the old man killed all of these people?
No. One street to the west. 2nd street from Wilshire (I think) South to Santa Monica is closed to traffic. There are also stalls on Arizona which runs East-West between Wilshire and Santa Monica. I think he barrelled down Arizona towards the beach and wiped out everything in his path.
The city should have put up substantial barriers to prevent this sort of thing. The reason they didn't is that trucks deliver produce and have to enter and leave often. Still, they could have blocked access with a truck.