Where does the past tense appear in this? Or is it implied?
It is implied.
I think it'd we weird to use any other tense in English. If the accident is currently happening, you'd know it was an accident (and probably be panicking not be chatting about it), and future makes no sense.
But what does it mean when you translate the Chinglish? Do you think there has been an accident - or do you think this is some kind of a coincidence?