Colombia Monday mourned the tragic loss of 32 children burned to death in a fiery bus explosion as authorities arrested the driver who had fled the scene of the inferno.

The youngsters -- aged one to eight -- perished Sunday after the bus burst into flames as they returned home from church services in the north of the South American country.

Another 20 children were hospitalized after the accident in the small town of Fundacion, in the department of Magdalena, according to the town's mayor, who said 32 children were dead, including two of the driver's own children.

"I am shattered, the entire country is in mourning for the death of these children," said President Juan Manuel Santos who rushed to the scene to console desperate families who lost loved ones.

"We will go through everything with a fine-toothed comb. Investigations are underway," he said.

Crews at the scene pulled little charred bodies from the blackened wreckage of the bus before transporting them to the medical examiner's office in the regional capital of Barranquilla to be identified -- a task which could take days.

Magdalena police told AFP the explosion occurred around noon, and that the fire was so intense they had problems determining the number of casualties.

Red Cross official Cesar Uruena said the injured -- taken to area hospitals -- suffered second and third-degree burns, and many were in critical condition.

Fundacion Mayor Luz Stella Duran declared three days of mourning and banned the consumption of alcohol.


'Driver detained after fleeing'

Local police announced Monday they had detained the bus driver who had initially fled the scene, prompting angry locals to hurl rocks at his home.

"The driver has been arrested. He turned himself in to authorities and we expect him to explain himself at a hearing this morning," a local police spokesman told AFP.

"He is in provisional custody as we determine his responsibility."

Survivors said the man, who has not been identified and was hired to drive the children to services at an evangelical church, continued driving the bus after it began leaking fuel.

Local media quoted an 11-year-old girl who lost two brothers as saying that, at one point, the driver got off the bus to refuel while his young charges remained on board.

"Sparks flew," she recalled. "It was then that the driver went to get water and then he left," she said.

"I broke a window and got my little sister out but I couldn't save my two brothers."

Investigators are looking into a number of potential causes of the disaster, which occurred a block away from the church where the children had attended services.

Among the possibilities being explored is that the driver tried to refuel the bus with a container of contraband gasoline and that this may have led to the explosion.

Transport Minister Cecilia Alvarez told RCN radio that the bus was overcrowded, had not been approved for service since 2012 and was not insured.

Santos traveled to Fundacion after a final re-election campaign rally Sunday in Bogota ahead of the country's May 25 presidential poll.

Accompanied by his wife, Santos said the government would pay for all hospital and funeral expenses relating to the accident.