A bus veered off a bridge and plunged into a canal in western India on Wednesday, killing at least 44 children and three adults, police said.
Rescuers pulled four surviving children from the 20-foot deep canal but several bodies remained missing.
The accident occurred in Vadodara, about 55 miles southwest of Ahmedabad, Gujarat's main city.
The state-owned public bus was carrying more than 60 children and some passengers from three villages in the region, officials added.
They said the driver lost control after one of the tires burst and ploughed through a concrete railing on the bridge, plunging the bus into the canal.
"I was sitting in the last seat and suddenly I felt the bus going down," said Sunil Thakore, 13, one of the few children who managed to swim to safety.
"I could see everything floating outside, and tried to call but there was no one around," the boy added, still shaking with fear. "I tried to pull my friend along, but it was impossible for me to swim with him."
The driver of the bus, an assistant and a woman passenger were among the dead, police said.
The children were studying at two separate schools and had taken the bus ride to reach their schools in time for their exams, police officers said.
'Died in front of our eyes'
Hundreds of villagers at Bamroli joined grieving parents to mourn the deaths with some claiming many children could have been saved if rescue operations started earlier.
"Children were screaming for help, some were struggling to swim but all of them died in front of our eyes," said Dharaji, a woman who goes by one name who lost her two daughters in the accident. "They promised to perform well in their exams but they died on their way to school."
Television pictures showed parents trying to identify their children from among rows of bodies laid out by the canal.
'All we could do was cry'
"For two hours I could see bodies floating in the canal, but nobody came to help us and all we could do was cry and scream for help," said Rambhai Thakore, a villager from Bamroli, which lost 15 girls in the accident.
"My daughter was going for her last examination today," Bhikiben, one of the bereaved mothers, told Reuters Television.
"She was very happy that her holidays were to begin, but now everything has ended for her," she said as authorities prepared to take her daughter's body to a local hospital.
Divers search for bodies
The state government ordered an inquiry into the accident and rushed medical teams to the scene.
The flow of water into the canal from a dam was stopped to help rescuers locate the missing people, district official Vijay Nehra said.
Rescuers used boats and officials said divers were looking for more bodies in the canal.
Many anxious parents, uncertain if their children were on the bus, were also seen rummaging through school bags recovered from the water to see if these belonged to their children.