Police officials said that the passenger van was traveling to Sehwan from Khairpur Mirs on Thursday evening.
When it neared the toll plaza, the van driver failed to spot the diversion and fell into breach which had been cut into a dyke during the recent floods.
Officials accused the van’s driver of driving recklessly and over speeding which caused him to miss the diversion.
Soon after the incident, police and rescue services rushed to the site. They pulled out the dead and 13 people who were still alive.
Dr Moeenud Din, the director of the Syed Abdullah Shah Institute, said that so far 18 bodies had been brought to the medical facility.
“Eight women, six girls and four children are among the deceased whereas two among the injured are in critical condition,” he said.
Sindh Chief Minister Syed Murad Ali Shah has taken notice of the incident and has directed the Jamshoro police to start a rescue operation in the area.