The death toll from a homemade bomb blast during a Christian prayer meeting in India has risen to three, police said Monday, as authorities questioned a man claiming responsibility.

More than 2,000 people were attending a three-day Jehovah's Witnesses meeting at a convention centre in the southern state of Kerala on Sunday morning when the blast and subsequent fireball ripped through the crowd.

Police said preliminary investigations showed the explosion was caused by an improvised explosive device.

One woman died immediately, and another died hours later of her wounds.

Local assistant police commissioner PV Baby told AFP on Monday that a 12-year-old girl had also died after suffering from burns covering much of her body.

"There are three to four people with serious injuries," Baby added.

The explosion happened in Kalamassery, near the port city of Kochi.

Hours later, a man handed himself in to the police after releasing a video message on social and aired on television channels, in which he claimed to be a disgruntled former member of the church.

Around two percent of India's 1.4 billion people are Christian, according to the last census in 2011.

There are nearly 60,000 Jehovah's Witnesses in India, according to the church's website.

Jehovah's Witnesses are members of a US-based Christian evangelical movement and are known for knocking on doors trying to convert people to their beliefs.

The movement, which preaches non-violence and is politically neutral, has a history of persecution, with its activities banned or restricted in several countries.