Is your latch that easy to open? You def need a way to secure it. A coyote or fox would have to be real good to open latch unless they used their noses to push it up. Can you post a picture of your set up?
A raccoon is most likely the culprit if the gate was unlatched. They can do just about anything we can with their hands. If this was at night I doubt they flew off but you never know hopefully they’ll be back.