Thiruvananthapuram, Four members of a family, including father, mother, and two children were found dead in a house at Kodungallur in Kerala's Thrissur district on Sunday.
The deceased were identified as Kadamparambath Ashraf (41), his wife Abeera (35) and their two children, Fathima (14) and Anoinsa (7).
The incident came to light after the family did not open the door even after forenoon and it was found that the house was locked from inside and the windowpanes were pasted with tape.
Police were informed and on breaking open the house, all four were found dead.
Sources in Kodungallur police said that the room where the four were found dead had a smell of carbon monoxide.
The Kodungallur police have registered a case of unnatural death.
According to neighbours, the family was going through a heavy financial crisis and owed money to several people.
M. Manikantan, a social worker from Kodungallur, told IANS: "This was unfortunate. He did not tell anyone about the crisis. People are getting isolated from society and are taking such extreme steps without solving them."
Police are conducting an investigation whether someone had threatened Ashraf and family or it was a suicide pact.