This is what I have in my .htaccess for my framework:
<IfModule mod_rewrite.c>
RewriteEngine on
#This will stop processing if it's images
RewriteRule \.(css|jpe?g|gif|png|js)$ - [L]
#Redirect everything to apache
#If the requested filename isn’t a file….
RewriteCond %{REQUEST_FILENAME} !-f
#and it isn’t a folder…
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^(.*)$ index.php?$1 [L,QSA]
#L = (last - stop processing rules)
#QSA = (append query string from requeste to substring URL)
</IfModule>
Hope this helps.
PS: Maybe you want to remove the lines to stop redirecting if it's a file or folder ;)