The photo has been taken from the doorway of the bus that was sent out to pick up the passengers, who were waiting inside the aircraft for the bus which was sent out to get them after the pilots made the decision to ask for the bus to come, then a contracted bus driver to be found, told where to go, and then drive out on the taxiways to get them - all the while the passengers with sitting in their seats.
Given the above sequence is likely to take in excess of 15 minutes, there's plenty of time to get some bags.