Sad story about my pets.

Hello guys, thanks for reading my post I really appreciate it.
I want to tell you that sad story which happened 4 days ago.

My dogs Luna and Onega were outside for maybe an 20 minutes. After they came back they behaved very normal, like every time they come back to home (I have them 8 years), they drink some water and do "dog things". After 2 hours they came back, Luna started to shaking really hard and vomiting. While I was talking with the vet Onega started it too I was so worried I went to the vet as fast as I can. In the cabinet vet gave them some medicalis and was like "Onega is fine at this moment, let's help Luna", but that was only the beginning of the real hell for me, both of them couldn't even breath properly, had 5 degrees of fever. The vet wasn't sure what she should do because she has seen something like that for first time, but she was trying her best to help them. After 15 minutes Onega passed out on my hands just in the moment I wanted to drive with her to the vet with more professional equipment, because I live in small town. With tears on the face I was like "Ok, I have second dog, which I have to save". I had to drive 50 km with Luna to the another vet and like 10 minutes from the place, she passed out too... two dogs died in so short time. So that's how I lost two members of my family. 

 Why?
After I back to my town and talk to the vet, she told me that they died from poison, but not from rat poison or something like that, that was sooo strong poison. They wouldn't found it like on the ground or in some food they could find because someone threw it. That was way stronger, strong enough to kill two healthy dogs so quick. Maybe im wrong, but for me that looks like someone have done this intentionally. But for what? I don't know.
If the dogs were doing some bad things to him he could come to me and be like "Heyy your dogs are doing bad things to me" and dont kill them. 

Sorry for bad english, that's not my main language.