Chi Yuanbing collapses on a bed after getting confirmation on Tuesday that his 7-year-old son was among the 15 students killed in a school bus accident in Fengxian county, Jiangsu province. He had been waiting to learn about his son's situation since he came to the county town on Monday evening. Gao Erqiang / China Daily

FENGXIAN, Jiangsu - The death toll in Monday's school bus accident in East China's Jiangsu province has risen to 15, a county official said on Tuesday.

The bus driver has been detained by local police, said Chen Likun, deputy head of the county's public security office.

Most of the students, all aged under 12, drowned after the 57-seat school bus of a primary school in Fengxian county rolled into a roadside ditch to avoid a pedicab.

Twenty-nine students were still aboard the yellow bus that was taking them home on Monday afternoon. A total of 23 injured children were rushed to local hospitals where 15 of them died while eight were still hospitalized.

No overcrowding a common practice for China's school buses and the cause of a long series of traffic accidents that kill dozens of students every year has been found in this accident.

But the driver, 30-year-old Hong Xu, who owned the vehicle, was suspected of driving it without a proper license, Chen said. Most of the school buses in the county are privately owned.

The tragedy comes after another school bus accident in inland Gansu province in November, which killed 19 students in an overcrowded vehicle, prompted the country's alert.

Yet on Tuesday, two other students were killed, and more than 20 people were injured, including seven seriously, in a bus collision in Zhumadian city of Central China's Henan province, local government authorities said.

The tragedies raised an outcry from the public and once again put the safety of China's tens of hundreds of school buses in the spotlight. It's estimated that China needs at least 1.5 million school buses if half of the nation's 180 million primary and middle school students use the vehicles.

The Ministry of Education has estimated there are about 285,000 school buses on the roads.

In Monday's incident, the bus rolled over in the ditch next to a large farm that grows winter wheat, drowning and suffocating the students stuck in the vehicle. Only six children escaped unscathed. Injured students were sent to two major hospitals in the county after receiving first-aid treatment at a local clinic.

"The site was very dark, and the road is very muddy and slippery," a crane operator surnamed Yuan, who helped in the rescue efforts, told China Daily on Tuesday.

He also said the dirt road was so narrow that it cannot allow two big motor vehicles to drive side by side.

Local villagers took part in rescue efforts before professional emergency workers arrived in five ambulances.

A man surnamed Tian, who worked for a nearby food processing company, said he and his co-workers had to jump into the freezing cold water to save the children after hearing their cries for help. The driver also participated in the rescue efforts.

On Tuesday morning, some schoolbags, textbooks and shoes remained uncollected on the surface of the muddy water and nearby ground. By afternoon, all eight injured were transferred to two better hospitals in Xuzhou.

In the Affiliated Hospital of Xuzhou Medical College, where five children were taken, one boy was receiving intense care at an outpatient department while four others were hospitalized in ICU.

"We arranged for our best medical professionals to care for them," said Zhao Peng, deputy head of the hospital's publicity department. She also said the hospital is still trying to help contact children's parents.

Outside the ICU, tearful loved ones were praying for the safety of their children.

Song Xinfeng, the uncle of two sisters both injured in the accident, said that 8-year-old Wanying and 6-year-old Mengying were the family's treasures.

"Their parents were out in big cities toiling as migrant workers. They have quit their jobs and are rushing home," said the tearful Song.

Mengying suffered slight injuries to her ribs while Wanying was still in ICU on Tuesday night.

"Except one child who suffered critical injuries, all the other seven injured showed stable symptoms," Zhang Bin, deputy county head of Fengxian, said at a news conference on Tuesday afternoon. "They even ate breakfast in the morning," he added.

Fengxian county, like many other regions across the country, was enforcing an overhaul on school bus safety when the tragedy occurred. Local government said that from Nov 20 until the end of the year, officers would ensure the safety of school buses and other important vehicles.

Following the incident, the Xuzhou education and work safety departments re-launched safety checks on all their school buses, and all school buses in Fengxian have been suspended to rule out safety loopholes.

Nationwide, all regional governments are urged to take a close look at school bus safety, said Huang Yi, spokesman of the State Administration of Work Safety.

"School buses that were involved in illegal operations and lacked proper safety protections should be strictly banned and not allowed to carry passengers," Huang said. He also urged society to make the safety of school buses and children a priority.