India's former President Avul Pakir Jainulabdeen Abdul Kalam died from cardiac arrest on Monday at the age of 83.

Kalam, popularly known as the "missile man of India," collapsed during a lecture at the Indian Institute of Management (IIM) in Shillong, the capital of the eastern Indian state of Meghalaya, on Monday evening, reported Firstpost. He was rushed to nearby Bethany hospital where doctors pronounced him dead.

"The former president was brought almost dead to our hospital," said John Sailo Ryntathiang, director of Bethany Hospital, according to Business Standard.

Kalam had tweeted just before leaving to Shillong earlier on Monday. "Going to Shillong to take course on livable planet at IIM," his last tweet said.

Prime Minister Narendra Modi, in his condolence message, described Kalam an "inspiration individual." "India mourns the loss of a great scientist, a wonderful President and above all an inspiring individual. Rest in peace Dr. APJ Abdul Kalam," Modi said, according to an official press release. "Dr. Kalam...my mind is filled with so many memories, so many interactions with him. Always marvelled at his intellect, learnt so much from him."

Indian President Pranab Mukherjee condoled the death of Kalam and said he was immensely popular and greatly admired.

"His warmth, humility and simple ways endeared him to one and all. He had a special love for children and sought to constantly inspire the youth of our country through motivational speeches and personal interaction," Mukherjee said in his message to the nation, according to Ndtv.

A.P.J. Abdul Kalam became the 11th Indian President and held the post between 2002 and 2007, according to PTI. He was popularly referred as the "people's president" during his term.

Kalam was instrumental in the nuclear bomb test in 1998 and India's missile program. He was conferred with India's highest civilian award, Bharat Ratna, in 1997 for his contribution to scientific research.