Thirteen people were washed away from a riverside restaurant at a village in Xi’an, capital of Sha’anxi Province on Monday evening.
According to local authority, seven bodies have been recovered and four people rescued.
Rescuers are expanding the search area to find the two missing people.
The rescue headquarters has sent five teams of police and firefighters, civilian rescuers and village officials to search the river.
Construction machines are used to dredge out the mud and rescue boats are cruising the river.
The Xi’an City Meteorological Observatory issued a yellow alert for the storm on Monday, warning that torrential rain may cause landslides and floods.
Local government says the precipitation at the village was recorded at 145.7 mm, the highest in the past 30 years.