At least 13 persons have died following heavy rain in Patna, Bhagalpur and Kaimur districts of Bihar.

The three districts are among over a dozen in the state that have been lashed by incessant rain for close to 48 hours, affecting normal business and disrupting rail and road traffic.

According to the meteorological department, the state capital has received more than 200mm of rainfall since Friday evening. Principal secretary (disaster management) Pratyay Amrit described the continuous rainfall as “totally unexpected”.

Amrit also expressed concern over water having entered many power substations, which could affect the functioning of sump houses.

After a video conference with district magistrates, chief minister Nitish Kumar told reporters: “We are making all possible efforts. I would appeal to the people of the state to have patience and courage. Torrential rain has followed a prolonged dry spell which vindicates our government’s resolve to combat climate change through environmental preservation.”

According to the Bhagalpur district magistrate, Pranav Kumar, three persons died when the boundary wall of a temple collapsed in Barari while as many people were buried alive when a house caved in at Khanjarpur.

In Danapur, on the outskirts of Patna, a one-year-old girl and three women died when a tree fell on an autorickshaw carrying them.

Three deaths were reported from Bhabhua, the district headquarters of Kaimur, where continuous rain led to the collapse of two mud houses.

From above, Patna resembled a vast lake dotted with concrete structures while low-lying areas such as Rajendra Nagar and Pataliputra Colony — home to many prominent citizens, private hospitals and medical stores and situated several kilometres apart — were submerged in waist-deep water.

“It was unexpected. The meteorological department had last week predicted heavy rainfall for many parts of Bihar but not Patna. We are trying our best to rescue people from inundated areas with the help of the NDRF and the SDRF. The sump houses are working overtime. However, water entering power sub-stations poses a challenge,” principal secretary Amrit said.

“In the event of water entering a substation, power has to be disconnected to avoid major casualties. The sump houses then become dependent on diesel. But the availability of fuel is finite and if heavy rainfall persists, efforts to pump out water from inundated streets could be hampered,” he said.

The East Central Railway headquartered in Hajipur said that close to 30 trains have been cancelled and many others “short-terminated” or operated on alternative routes on account of the flooding of Patna and Danapur junctions.

In Nawada, water has crossed the danger mark, threatening residents of five villages even as efforts were on to trace three locals who were reportedly swept away by the current.