Because prepositions can often by exchanged for one another (in this case the prepositions are "by" and or"), either way is grammatically correct in this sentence. I tripped on accident or I tripped...
By accident (As 'by' is being used as a stand in for 'as a result of an', which is similar to, 'as a result of an action of Jeff', or 'by Jeff')This also raises the question "why is it 'by accident'...
Don't run is the first thing; make sure everyone is okay and out of harms way; out of the traffic - call for the police. Exchange driver's license information, insurance information. If anyone is...