Can someone help identify a snake for me please?

I live in Thailand and last weekend while clearing brush on my property i uncovered three snakes. They were all about2.5-3 feet long and bluish gray in color. Their heads were not triangular and they had an interesting sort of iridescence when they ped through a patch of sunlight. I have two little kids so I want to know if they are dangerous or not. Thanks for your help.