What is the condition to get a rampage in Dota 2

In Dota 2 we need to kill 5 enemy heroes in a short time. But what is the exact time? Or do we need to kill each hero within 10 seconds from the previous one?

I don't find any official documentation on that.


Solution 1:

According to this thread on Reddit, unfortunately without further source, it is a maximum of 17-18 seconds between kills.