I believe that the minimum raise is 10 more to 20, which is what the initial bet was. The all-in didn't make a full raise, so his raise doesn't count...I think...
If the 1st guy bets $10 and the second guy calls and the third guy goes all-in for $16, then the 1st and 2nd players can't reraise because the 3rd player didn't make a complete raise.