Three days after three teenaged boys died of suspected food poisoning at a private residential school in Karnataka's Tumakuru district, a fourth death was reported on Sunday.

The school’s security guard, 45-year-old Ramesh, who was being treated in the Intensive Care Unit of Tumakuru district government hospital died around 10:45 am on Sunday, reported The Hindu.

“The security guard died of cardiac arrest,” district surgeon of Tumakuru district government hospital Dr Veerabhadraiah told The Hindu.

The Karnataka government had ordered the district administration to investigate the matter on Thursday.

"The boys, students of Vidhyavaridhi International Boarding in Huliyar town, are suspected to have died of food poisoning, as they fell seriously ill after eating rice and sambar on Wednesday night and were rushed to a hospital for treatment," Tumakuru Deputy Commissioner Mohan Raj had told IANS on Friday.

They were identified as Shanthamurthy, Aakansha Pallakki and Shreyas, aged 14-15 years and studying in classes 8 and 10.

Huliyar is 160 km from Bengaluru.

"Four persons – the mess in-charge Suhas, head cook Shivanna, assistant cook Rangalakshmi and attendant Jagdish - were arrested for culpable homicide as the boys were under their care," Tumakuru Superintendent of Police Isha Pant told IANS.

The police had also arrested the owner of the school, former BJP MLA Kiran Kumar.

Police registered an FIR against the accused under section 304A of the Indian Penal Code, causing death by negligence, on a joint complaint by the victims' parents.