A suspected bomb blast during a Christian prayer meeting in India's southern state of Kerala killed two people and wounded more than 35 others, police said Sunday.
More than 2,000 people were attending a three-day Jehovah's Witnesses meeting at a convention centre in Kalamassery near the port city of Kochi when the blast ripped through the crowd.
"At about 9:40 am (0410 GMT) approximately there was an explosion in Zamra International Convention Centre in which one person died and 36 are undergoing treatment," Director General of Police of Kerala Darvesh Saheb told reporters.
"We will find out who is behind this and take stringent action... preliminary investigation shows it was an IED (improvised explosive device) blast."
Local assistant police commissioner PV Baby, speaking to AFP, said one women died in the initial explosion, and a second woman later died of her wounds.
A man handed himself in to the police after releasing a video message on social media and aired on television channels, in which he claimed to be a former member of the church who now disagreed with its beliefs.
Police said they are "examining his claims and the reasons given for carrying out the act", according to The Times of India.
The Press Trust of India (PTI) news agency reported at least three "blasts" had occurred inside the convention centre.
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 perhaps best known for knocking on doors around the world, bible in hand, 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.
It is a millennial faith, meaning its members believe that the end of the world is near and that God's kingdom will soon rule over the Earth.
The blast comes against a backdrop of inter-communal tensions within the prosperous southern state of more than 31 million people, 26 percent of whom are Muslims, according to the census.
"I would request everyone to maintain peace, remain calm, and I also request that no provocative posts are made on social media," Saheb added.
The explosion came a day after former Hamas leader Khaled Mashal addressed a pro-Palestinian rally in a pre-recorded message in Kerala's Malappuram, around 115 kilometres (71 miles) to the north.
There was no indication that the events were in any way connected, but social media carried several posts connecting the speech and the blast.
The inclusion of the senior Hamas official drew condemnation from the ruling Hindu nationalist Bharatiya Janata Party (BJP).
Mashal's address to the rally was organised by a youth solidarity group affiliated with the state's branch of the Islamist Jamaat-e-Islami Hind party.