During a tournament game that was 1-1 a representative from the complex yells “Heads Up” do to a foul coming towards the field we were playing on. There were runners on 1st and 3rd with 2 outs. The pitcher stopped her motion and looked up along with other infielders. The umpire calls an illegal pitch and has both runners advance, which resulted in the runner on third scoring the winning run. The umpire said he didn’t hear it even though everyone else did and the 1st base umpire said nothing. What’s the right call? Should the runners have been allowed to advance?