What to do when someone rings you doorbell at 4:30 am?

I woke up with constant barking of a stray dogs. Which is not that uncommon. Until now, because my society has a lot of houses and apartment buildings, I used to go out and scare the dogs away no matter what time it was because I believed no one would dare committ a crime when help was just a shout away. Idk. This is a safe society overall. So I did not wear my specs. Grabbed and coat and climbed down the stairs. I was only a couple of stairs away from the bottom, when I heard the doorbell ring. Coincidentally, I was right at the line of sight of a window that looks outside to the porch, the garden & the main gate. I saw someone standing there. In my sleepy haze I thought that it might be my uncle or my cousin, who sometimes drop by our house this early when they catch a train back home from somewhere. Because my house is closer to the train station and they live in a town 2hrs away. I have two dogs. One was up but was not barking. I opened the door slightly and slipped out through the crack (because I did not want them to go out as they create a ruckus to treat guests). The person who was standing there didn't initially see me (because I opened the door ever so slightly). But when I started walking towards him, he saw me and he walked away briskly (he did not run). Stupid me, thought my uncle went to take his stuff out from his car. And I waited at the main gate. When he did not come back, I stepped outside the main gate and looked around (I know it is getting stupider). The stray dog that woke me up initially with his barking was now barking in the direction that the person went. Also, one important thing to note is that. The street light that focuses on our house is very bright almost like a big halogen. Which made me think that it was 5 or 6 o'clock. I didn't realise it was 4:30. This is when I realised something is wrong. And I rushed inside. I woke my parents up and told them everything. This is where is gets even creepier... My mom listened to everything and then told us this. My mom usually falls asleep on the couch that is right next to a huge window that faces our garden. The shades were half-drawn. Now, this window shakes when three things happen. 1. When someone closes the upstairs bathroom door. (Idk why) 2. When it is windy 3. When someone touches it (maybe to open. It has grills but the sliding window itself does not have a lock, unlike other windows in my house.) Mom told us that the window shook, she peered outside and didn't see anyone. So she turned on the garden lights and hurried upstairs to check if anyone was using the upstairs bathroom. This was around 2-3 am. My dad & I were fast asleep. She thought she was overreacting and went to sleep. Now I am unable to sleep. I'm writing this while my dogs are slowly growling looking towards the window and the door.... I am fucking scared. What was this? What should I do?