SHANGHAI -- Four people were killed and another 40 injured Sunday in multiple pile-up accidents along an expressway in Shanghai, local authorities said.

Several road accidents were reported along the S32 expressway in Pudong New Area on Sunday morning due to foggy weather, and as of noon time, hospitals of Pudong, Zhoupu and Shuguang had received 44 people, according to a statement issued by the Shanghai municipal health department.

Four of them died despite medical efforts, and among the other 40, nine were seriously injured, said the statement.

Shanghai weather station at 6 a.m. issued an orange alert on heavy fog, the second highest level in China's weather alert system, which means a fog with visibility of less than 200 meters in the following six hours.