Sadly, with any mass participation event, security is never going to be tight enough to stop this....it would take too long.
Look at the London marathon start - I've done it 4 times, starting from the Red area (the one you see on TV with all the fun-runners, rhinos, fat people (me!) etc!!!).
30,000+ people.....all packed tightly.....would make a nice target don't you think?
Then look at those in fancy dress? Why is that rhino ticking?
Security at the start? ok, they have marshals to stop non-runners entering the starting pens, but you could easily jump the barrier, but no need, as spectators line the edges, and as we saw yesterday, any such device doesn't need to be in the middle of the crowd.
Yesterdays attacks...if they are proven to be so...didn't kill, injure that many people when you think about it (I'm not saying it doesn't matter). But what they did do was get press coverage.
At the end of the day, in this world where people will cause death and destruction for their cause, then the fact is, no one is safe. Security is in place, in my opinion, to make people feel safe, to look as if something is being done. Take airport security.....how come I walked through a metal detector at one airport with NO reaction, yet when walking through the metal detector on the return journey, with the same things, the alarm went off?
One day I was entering a theme park and all bags were being inspected. The guy in front had a pen knife that the security found...the guy said "its only a penknife"....the guard put it back and let him through!
London Marathon runners....you put your kit in a bag at the start, put it on a lorry which is transported right into the secure zone at the finish line. Do they check those bags? They didn't a few years ago.
I hope the people responsible rot in hell and that there 70 virgins come to me instead!