Help!! On my yard under the roof of the small kids wooden house I found a sparrow nest I guess. There were 6 eggs altogether.?

I saw a female sitting in the eggs all the time. A few days ago the eggs hatched and there were 6 little birds inside. Yesterday I noticed there were only 2 little birds left. Today I haven't seen their mother yet. It's 8 pm :( I don't want those cuties to die. What do I do? Should I wait for their mum?
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