Everyone wants to take a knife for granted - but once you are close, a knife is a better weapon than a gun. It's a LONG video, but when you have some time, go watch 'Surviving Edged Weapons' on YouTube. If you want to know how 5 people, (or more)can be killed FAST by 1 guy with a knife, this video will clear things up:
Thanks, a bit long but that's a good video on knife attacks.
It has some good interviews and images ( *graphic images warning*), but it is well worth watching. The lesson here would be, armed with a firearm or not, you underestimate a knife, any knife, at your own risk.