How did my FIL take photos of himself?

So a couple of days ago my FIL was driving home from work when he noticed the beautiful sunset (he's always taking photos of sunsets and sunrises) so he pulled over, walked down near the water and took a few photos on his phone while turning on the spot. At the time there was nobody anywhere near him and he saw nobody in the photos or for that matter nothing unusual, but as soon as he reviewed them there was a person in all but one and when he zoomed in he could see it was himself and you can see clearly that the phone that he's taking the photos with is in the photos! Needless to say he was pretty freaked out and got back in his car and drove home. Does anyone know how this could have happened? When he explained it to me I thought at first he had flipped his camera by accident but as soon as I saw the photos I knew that couldn't be the explanation, the photos are taken from much further away than possible with the other camera, let alone the fact that they are taken from behind and the phone is in the photos too. To me it kinda looks like someone is walking behind him and taking photos as they go, it's very weird and nobody we know can explain how it happened. I've known this man for over 25 years and he was genuinely freaked out and even talking about it seemed to kinda scare him so I know he didn't fake this. Note: it's absolutely him in the photos, i can tell beyond a doubt.