Hi, I had the same thing happen a couple of days ago. The fox was in my garden at 11:30am! He then went into my neighbours for a while and ran off as soon as he saw me. I realised he was eating apples! Although, I didn't let my hens out that day I let them out yesterday, but I walked around with them.
So, you could let them out if you walk around with them, but don't leave them alone for a minute as I've read post that the fox could snatch one in front of you. V. scary.