Things can go wrong on a big scale,as a number of people rec

Things can go wrong on a big scale,as a number of people recently discovered in Parramatta,a suburb of Sydney.During the rush hour one evening two cars collided and both drivers began to argue.The woman immediately behind the two cars happened to be a learner.She suddenly got into a panic and stopped her car.This made the driver following her brake hard.His wife was sitting beside him holding a large cake.As she was thrown forward,the cake went right through the windscreen and landed on the road.Seeing a cake flying through the air,a lorry driver who was drawing up alongside the car,pulled up all of a sudden.The lorry was loaded with empty beer bottles and hundreds of them slid off the back of the vehicle and on to the road.This led to yet another angry argument.Meanwhile,the traffic piled up behind.It took the police nearly an hour to get the traffic on the move again.In the meantime,the lorry driver had to sweep up hundreds of broken bottles.Only two stray dogs benefited from all this confusion,for they greedily devoured what was left of the cake.It was just one of those days!
Why did the woman in the car behind get into a panic?
求求大大回答...小弟将感激万分(文法必须正确)