Maggie ran back to the kitchen, eggs( )carefully in her hand

Maggie ran back to the kitchen, eggs( )carefully in her hands;答案为held,为什么呢
鸡蛋应该是被拿在手上,被动语态的形式不是be+过去分词,为什么不是选were held呢而是held,能给分析以下吗