Do interrupts interrupt other interrupts on Arduino?

I have an Arduino Uno (awesome little device!). It has two interrupts; let's call them 0 and 1. I attach a handler to interrupt 0 and a different one to interrupt 1, using attachInterrupt() : http://www.arduino.cc/en/Reference/AttachInterrupt.

Interrupt 0 is triggered and it calls its handler, which does some number crunching. If interrupt 0's handler is still executing when interrupt 1 is triggered, what will happen?

Will interrupt 1 interrupt interrupt 0, or will interrupt 1 wait until interrupt 0's handler is done executing?

Please note that this question specifically relates to Arduino.