At least 22 people died when a tourist boat capsized in India, officials said Monday, with many of those on board thought to be children.

It was not clear why the double-decker boat carrying at least 30 people tipped over in the southern state of Kerala’s Malappuram district late Sunday.

Dozens of people searched for survivors in and around the stricken vessel all night, which was partially submerged, and the search continued into Monday.

Some used ropes to stabilise the boat while others were in the water, desperately looking inside the vessel’s windows for any survivors.

“We have recovered 22 bodies, including 15 females and seven males. There are around six people in the hospital. Rescue operations are on,” a police officer told AFP.

Local publication Onmanorama reported that 11 people from one family, including three children, had died in the accident.

Rajisa, who was on the boat with her husband and daughter, told the publication most of the passengers on board were children and that there was smoke coming from the boat during the journey.

“We survived only because we were wearing life jackets,” Rajisa, who bruised her neck after hitting the boat, was quoted as saying.

She said three life jackets were brought to her and her family, and four jackets were given to children on the boat’s top deck.

“The boat swerved sometime after it set sail. Everyone was thrown off to one side as the boat wobbled,” she told Onmanorama.

“I fell before my child and sank into the water. The boat overturned on top of the people who had fallen into the water. There were mostly children on the boat,” she said.

Broadcaster NDTV said rescue teams, including personnel from National Disaster Response Force and the Indian Coast Guard, were using underwater cameras to look for those still missing.

VD Satheesan, a politician from the opposition Congress party in the state, said the accident was “man-made” and called for a probe.

“Nobody even knows if the boat had a licence or not,” he said Monday, speaking to reporters.

A case has been registered against the boat’s owner for alleged culpable homicide, media reports said.

Kerala’s sports and fisheries minister V. Abdurahiman, who was helping to coordinate rescue efforts, said most of the victims were children on school holidays.

Police said that there were around 30 people on board.

But NDTV reported that 40 people had tickets, although there were many others on the vessel who did not.

Abdurahiman said four people were taken to hospital in critical condition, according to the Press Trust of India news agency.

“Pained by the loss of lives due to the boat mishap in Malappuram, Kerala. Condolences to the bereaved families,” Prime Minister Narendra Modi said on Twitter, adding that families would get compensation.