Collision In A Run Down

[UnsureAboutCall]

Say we have a run down between first and second. After a few back and forths between first and second the runner commits to second base and is clearly making a run for second. The player who at the time is covering second base gets the ball and begins to run at the runner who is running to second, so they are both running at each other. A collision ensues as neither player was unable to get out of the way of the other. Would the call be obstruction or interference?