Translation:We are running because of the bear behind us.
Since this has come up a time or two when the programme insists on "due to" as a preposition and refuses to accept actual prepositions such as "owing to" or "on account of" (here it did accept "because of"):
"Due to" is not really a preposition; it's an adjective that takes what amounts to a dative complement. I.e. thus: "My being short on cash is due to the larger than usual power bill that I had to pay this month." Here "due" is clearly an adjective modifying the gerund "being".
When you switch the sentence around a bit the adjective loses its raison d'etre:
"I am short of cash owing to (or "on account of" or "because of", but not "due to") the larger than usual power bill". Here you need an actual preposition.