Two women died and 51 persons were injured, some seriously, in multiple blasts at a Christian religious gathering in a convention centre near this port city on Sunday morning, sending shockwaves across Kerala.

The blasts took place at an international convention centre in Kalamassery where hundreds of followers of the minority Christian group Jehovah's Witnesses had assembled on the concluding day of a three-day-long prayer meeting.

A few hours after the incident, a man claiming to be a member of Jehovah's Witnesses, surrendered before police in Thrissur district of the state, saying that he carried out the multiple blasts.

Police has registered an FIR against unknown persons under Sections 302 (murder) and 307 (attempt to murder) of the IPC as well as provisions of the Explosives Act and the anti-terror law Unlawful Activities (Prevention) Act (UAPA).

Later in the day, state Health Minister Veena George said that of the 51 injured, 30 were admitted in various hospitals in the state and of them 18 were in ICUs.

Of the 18, six -- including a 12-year-old child -- were in critical condition with three of them having suffered over 90 per cent burns, the minister said. She said teams of plastic surgeons and general surgeons arrived at Kalamassery Medical College from Thrissur and Kottayam medical colleges.

Besides that a 14-member medical board was also constituted to supervise the treatment being provided to the injured.

ADGP Law and Order M R Ajith Kumar told reporters here that a man named Dominic Martin had surrendered at Kodakara police station in the morning, claiming he was the one who set off the blasts.

The officer said the man gave evidence supporting his claim and the police were examining that as well as his claims and the reasons he gave for carrying out the act.

Prior to surrendering before the police, the man also put out a video message on a social media platform claiming responsibility for the blasts and stating his reasons.

In the video, which was aired on various TV channels, the man claimed that he took the decision as the teachings of the organisation were "seditious." No one from the organisation has reacted to his allegations.

Meanwhile, a person claiming to be a member of the religious group told a TV channel that no such person was part of their organisation presently.

Martin further claimed that Jehovah's Witnesses and its ideology were dangerous for the country and therefore its presence had to be ended in the state. He claimed that he had told the organisation several times to correct its teachings, but it was not ready to do so.

"As I had no other option, I took this decision," the man said.

Earlier, State Police Chief Shaik Darvesh Saheb told reporters in Thiruvananthapuram that according to the preliminary probe, an improvised explosive device (IED) was used to carry out the blasts.

Jehovah's Witnesses is a Christian religious group that originated in the United States of America in the 19th century.

"This morning at 9.40 am approximately, there was an explosion in Zamrah International Convention Centre in Kalamassery in which one person died and 36 people are undergoing treatment as per our information," the DGP said.

"We are examining it," he said, adding that a Special Investigation Team (SIT) will be constituted once he reaches the site.

A police source told PTI that there were three blasts, of which two were strong and the third was of low intensity.

On being asked whether tiffin boxes were used for packing the explosives as claimed by some news reports, the source said that it cannot be confirmed at this stage as the blast site was being examined by multiple agencies, including the state anti-terrorism squad and the National Investigation Agency (NIA).

Earlier, before Dominic Martin had surrendered, the DGP said he cannot say anything at this stage, and only after further investigation can he confirm whether it was an act of terror.

"Only after the investigation can I confirm the details. We are examining all the angles. We will find out who is behind this and take stringent action against them," the top police official said.

He also urged people to maintain peace and remain calm and asked them not to spread provocative or hateful messages on social media.

The spreading of provocative or hateful messages on social media would invite strict action, he warned.

The incident was termed as "shocking" by Kerala Governor Arif Mohammed Khan and "extremely unfortunate" by Chief Minister Pinarayi Vijayan.

"Shocked to hear about the blast at a religious gathering at #Kalamassery, Ernakulam district, Kerala, killing one person and injuring over 20. "Heartfelt condolences to the kin of the deceased and prayers for speedy recovery of the injured," the Governor said in a post on social media platform X.

Speaking to reporters in Delhi earlier, before reports of the second death in the blast, Vijayan said, "It is an unfortunate incident. One person died, and two others are in serious condition. An investigation has been launched, and further details will be available later. The incident is being viewed very seriously." The CM also convened an all-party meeting on Monday in the wake of the blasts at the convention centre.

CPI(M) State Secretary M V Govindan, who is in Delhi along with Vijayan for some party programmes, said any terrible actions aimed at diverting attention from the Palestine issue would entail strict action.

"When Kerala stands united with the people of Palestine, any terrible action to divert attention from it will entail strict action. The government and all democratic persons will together condemn it," he said.

Govindan also said that on viewing the incident politically in the prevailing situation, it appears to be part of a terror act.

"That needs to be examined seriously," he said.

Kerala Revenue Minister K Rajan said no one, including the media, should take any steps or circulate information based on misconceptions about the incident.

Eyewitnesses recounted the terrifying moments following the blasts which occurred minutes after attendees began praying with their eyes closed.

Recounting her shocking experience, an elderly woman said, "When I opened my eyes after hearing the first blast, all I saw was a fireball in front of me.

"Nothing...nothing more...just a fireball. Everybody ran, scattered here and there. It was a sprawling hall, and a large number of people were inside." Among the distressed crowd at the venue were senior citizens, including women who had participated in the morning prayers.

A man in his 70s, his voice trembling, described the shock of witnessing a blast in the midst of the densely populated prayer convention.

In all his years of attending the convention, he said, he had never witnessed anything like this before.

Visuals of the incident on TV channels showed fire rescue and police personnel in large numbers evacuating the site.

Disturbing visuals of the situation inside the convention centre shortly after the blasts showed multiple fires inside the hall as people and children were heard screaming in fear.

The video also showed some people trying to quell the fire as the hall was littered with scattered and broken chairs, many of which were ablaze.

Following the blasts, police and district administrations across the state were put on alert.