这句子谁写的，其它错误一并纠正

I was on my way to the bookstore and was waiting for the green light at a crossing when a girl of about ten was knocked down by a passing car, which drove off quickly.

when在这里表示突然，句子表示的是女孩突然被车撞了。

如果你用it，你要表达的是汽车突然跑了，即使如此也要把“汽车突然跑”放在when之后，所以肯定是错的。