Hello, my daughter has been waking up every night around 3-4 am for a …

Hello, my daughter has been waking up every night around 3-4 am for a week and starts crying very loudly, kicking her legs. Once I tried to wake her during an outburst, washed her face but it didn't get any better. We have never had sleep problems before. But these outbursts scare me. How can I find out the cause? I don't even understand why this might be happening? And that she kicks with her legs, maybe something is bothering her? She talks well with us, if it bothered her I would already know about it. But here I am in complete bewilderment!