整个句子要注意协调性哦,可以参考下面这个翻译:
She called the police the moment she saw the thief.
这里的the moment就是指的“那一刻”,那一瞬间了,很好地传达了楼主的意思
希望可以帮到你
Once she see the thief she call the police
Once seen the thief, she called the police.
Once seen the thief, she call the police.