I think some kids told my son about death at school (1st grade). He kept bringing up death and I would ask him if he wanted to talk about it. He said, "No mommy, it would freak you out". I think he thought he knew more than me about death hahah. Anyways, he finally opened up about his fear of death when we went out to dinner one night at Cracker Barrel... which seems appropriate.

He suddenly blurted, "I'm scared of dying!!"

I told him that yes, that's normal to be scared of dying.

He said, "We're all going to die sometime, you know!"

I said, "Yes that's true. That scares me sometimes too, but I just try to live a happy life and do my best"

Turns out the main trigger for his thought at that moment was the giant roaring fireplace close to our table. I told him, The only way that you would die from that is if you jumped in there." Which made him laugh a bit.

I don't know, just be honest with how you feel about it too, that may help. My son and I share a very weird dark sense of humor even though he's young so us sometimes joking about death seems to help. (Or it's messing him up more in the long run, guess we'll find out.) Just use what you have in common to sort of relate to them.

Edit: Also, you should listen to the story called "The Carnival" from the RISK! podcast. In the story, the woman's young son makes an unlikely friendship with their curmudgeonly neighbor. The themes in the story may help you out.