All players disconnected and both teams ended in defeat

First game of the season – we were playing the game normally, past 7 minute mark, I got disconnected. I thought it was just my internet, so I checked the network and it was running fine, so I restarted the game. However, it didn't let me reconnect. Restarted my computer- it didn't work as well. When I closed the game, the client appeared as if the game was finished. I checked the match history and OPGG and we were defeated (both teams). I was able to download the match and saw that all players got disconnected.

Does anybody know what could've caused this? I don't wanna play ranked for now just in case this isn't a one time thing.