One person was killed and dozens injured when at least one homemade bomb exploded at a convention centre in the southern Indian state of Kerala on Sunday where a Christian group was holding a prayer meeting, police said.

Preliminary investigation has shown that an improvised explosive device was used and that 36 people were injured, Kerala Director General of Police Shaik Darvesh Saheb told reporters.

Local newspaper Mathrubhumi, citing witnesses, said at least three explosions occurred inside the convention hall.

When asked whether it was a terror attack, Saheb told reporters, “at this stage I cannot say anything; only after investigating I can confirm the details”.

State Transport Minister Antony Raju said more than 10 people have suffered serious burns and were in critical condition.

The incident took place during a Jehovah’s Witnesses convention at the centre in Kalamassery, about 10 kilometres (6.21 miles) northeast of Kochi. The group was holding a three-day zonal convention that had seen more than 2,000 attendees, according to local media.

Kerala Chief Minister Pinarayi Vijayan said the incident was very unfortunate and that the police have taken it very seriously.

Police was appointing a special investigation team, Saheb told reporters, adding that strict action would be taken against those involved in the incident.

An eight-member team from the National Security Guard, the Indian government’s counterterrorism unit, is on its way to Kerala to investigate as well, media reported.

The health and medical education departments have been instructed to provide high-quality treatment, said Kerala’s health minister, Veena George.

“The explosion occurred seconds after the end of a prayer as part of the day’s event. The first blast took place in the middle of the hall. Seconds later, two more explosions rocked simultaneously on either sides of the hall,” TA Sreekumar, regional spokesperson for the Jehovah’s Witnesses told mathrubhumi.com.

Jehovah’s Witnesses are an international Christian denomination that was founded in the United States around 1870. They are best known in many countries for door-to-door evangelism.

The group says it has about 60,000 followers in India. The Supreme Court of India in 2022 backed the church’s members in Kerala when some Jehovah’s Witnesses children stood for the national anthem but did not sing it, citing their faith.

In March, a gunman killed six people at a Jehovah’s Witnesses hall in Hamburg, Germany.