This was a road.
Carol suggests taking this route to get back home after having seen the downed bridge.
In the woods, the wagon gets caught in the mud as walkers appear from the bushes. It finally refuses to budge and everyone rushes to gather the supplies until the walkers overwhelm them and they're forced to leave. Ken runs back to free his horses but is bitten in the arm by a walker and then kicked in the ribs by the horse.
Siddiq and Enid try to save him but Ken succumbs to blood loss and dies from his injuries. A saddened Maggie sobs by his side before putting him down.