Twenty-six passengers were rescued by a combined team of the National Disaster Response Force and Civil Defence personnel on Friday evening after they remained trapped on a country boat on a canal of the Hooghly in Nadia's Santipur for about nine hours as dense patches of water hyacinth chocked the surface of the canal.

The rescued people included 18 students and the boatman.

The students aged between six and 14 study from Class V to Class VIII at Bagh Anchra High School and hail from Char Panpara, Khounishnagar, Kaldanga, and Krishnadevpur villages. They were on their way to school at Bagh Anchra on the other side of the canal that draws water from the Hooghly.

Sources said at least four students fell sick as they remained stranded in the scorching heat since 9am. The harsh sun left the students parched and they had no water to drink for most of the day after their water bottles ran dry.

As the children remained stranded, their parents and local residents watched helplessly as boat after boat tried but failed to cut through the dense hyacinth barrier to rescue the students.

Water hyacinth is an invasive fast-growing aquatic weed that surfaces on water bodies and forms daughter plants, which can reproduce thousands of seeds to remain viable for over 20 years.

"The staunch hyacinth weeds remained immovable as the district administration never bothered to clear them for months despite repeated requests. The kids had to pay the price for the negligent attitude of the administration," said a local resident after the passengers were rescued around 6.30pm.

"It took three hours of rigorous efforts by Civil Defence and NDRF personnel to cut the floating weeds and create a passage to the trapped boat," said BDO Santipur Md Sabbir Ahmad Molla, who monitored the entire rescue operation.

A large number of people cross the 400-meter stretch of the Chari Ganga to reach their destinations.

People prefer the boat service from Char Panpara ghat to reach Bagh Anchra ghat, which is the gateway to Santipur, as a road trip to the other side entails a detour of 11km.

Ashim Hazra, father of Class V student Shreya who was among those trapped, said: "Every day I drop my daughter at the Char Panpara ghat at 9 am so that she can reach school on time. But on many days, the journey is delayed as the boatman takes time to remove the weeds and move ahead. Today, a sudden gust of wind pushed the hyacinths all around the boat, leaving the kids trapped."

Speaking to The Telegraph, Nadia district magistrate S. Arun Prasad said: "Today our focus was on the rescue. We will discuss the technicalities involved with the departments concerned and find out the cause for the growth of hyacinth. Once we do that, we will examine ways to clear the weeds."