Eight passengers on a motor boat died after it was hit by a fishing boat and broke near Fort Kochi on Wednesday afternoon.
Police supervising the rescue operations said the passenger motor boat was carrying over 30 passengers who were going to Vypeen island from Fort Kochi.
According to a witness, the fishing boat was reversing when it hit the passenger boat.
"The accident took place about 100 metres from the Fort Kochi boat jetty, which is the international shipping route. Hence, even if someone is a swimmer, it's difficult to survive," said Samson, the witness.
"The place is frequently dredged and hence the place where the accident took place is very deep," Samson added.
Police said as soon as the accident occurred, the navy and the Coast Guard swung into action and rescued around 20 people even as the boat was sinking.
Some of those rescued died after being taken to a nearby hospital. Most passengers were residents of Vypeen, and all but one of the dead has been identified.