Rail services were affected as flood waters submerged tracks at many places. Several trains had either been diverted or cancelled, East Central Railway Chief PRO Rajesh Kumar told .
A railway official, however, said the train services were resumed on Saturday morning.
According to officials, the water level in Koshi river is increasing continuously and at the Gandak barrage it has risen sharply due to heavy rain in the Terai region of Nepal.
Stating that the state government is on high alert to tackle the situation, Pratyay Amrit, Principal Secretary at the Bihar State Disaster Management Authority, said six districts Sheohar, Sitamarhi, East Champaran, Madhubani, Araria and Kishanganj had been affected.
The relief and rescue works were underway, he added.
According to a state disaster department official, the rising water levels of Koshi, Gandak, Budhi Gandak, Ganga and Bagmati have caused panic among the people living along the river banks.
According to reports, hundreds of people have fled or are fleeing their homes in Supaul, Muzaffarpur, East Champaran, West Champaran, Araria and Kishanganj districts.
The Water Resources Department had issued a high alert in vulnerable districts, particularly those that border Nepal, said an official.
North Bihar districts received a record rainfall during the last 24 hours with East Champaran reporting 214.92 mm rain, Sitamarhi 154.55 mm and Muzaffatpur 125.15 mm, said Met Department officials.
In Motihari, district headquarters of East Champaran, incessant rainfall for the last four days caused waterlogging in the town. District Magistrate Raman Kumar had ordered closing of schools and other educational institutions till July 15, district disaster officer Anil Kumar said.
Schools in Araria and Kishanganj districts have also been closed.
Though the rising water levels have increased pressure on embankments at several places, officials claimed they were safe and there was no need to panic. The state government has alerted engineers concerned and asked them to keep 24-hour vigil.
"All engineers have been directed to be ready with necessary equipment and boulders to face any situation and protect the embankments," an official of Water Resource Department said.
( With inputs from IANS )