Sri Lanka police have arrested seven people during a raid on a residential house near the eastern city of Kalmunai in connection with the suicide bombings on churches and hotels that left more than 250 people dead.

During the search operation in Sammanthurai, police said they found suicide vests, explosives, a drone and a flag with an Islamic State logo.

Six kilometres away, in the coastal city of Sainthamaruthu, a gunbattle erupted between police and a group of armed individuals during another search operation conducted at two houses.

Three explosions were heard at one of the houses before the shootout began. The blasts were believed to have been triggered by the raid.

Seventy-six people have been detained in connection with the suicide bombings with police issuing a warning of the risk of further attacks, specifically on religious targets, closing churches and mosques.

Cardinal Malcolm Ranjith told a press conference on Friday (local time) that Sunday masses in the city would be cancelled until further notice. And many – although not all – mosques cancelled weekly prayers, which are generally attended by larger numbers of worshippers on Fridays.

Breaking: Explosions and gunfire reported as Sri Lankan security forces raid an ISIS bomb factory in Kalmunai, Sri Lanka. https://t.co/pLrZIygCL7

— PM Breaking News (@PMBreakingNews) April 26, 2019

Meanwhile, Sri Lanka’s Prime Minister Ranil Wickremesinghe told the BBC he was “out of the loop” about intelligence warnings ahead of the deadly Easter Sunday bombings and did not need to step down from his position.

Mr Wickremesinghe said crucial information about any potential danger in the country was not passed onto him.

“If we had any inkling, and we had not taken action, I would have handed in my resignation immediately,” he said.

“But what do you do when you are out of the loop?”

According to intelligence reports cited by police, Islamic fundamentalists led by militant Zahran Hashim were also planning to strike mosques from the Sufi branch of Islam. Some Muslim fundamentalists regard Sufis as heretics.

Zahran is the suspected mastermind behind Sunday’s fatal blasts, which targeted three churches, three luxury hotels and two other locations and left 253 people dead.

President Maithripala Sirisena confirmed on Friday that Zahran was one of the suicide bombers.

The US embassy in Colombo warned the public to avoid places of worship from Friday until Sunday.

“Terrorist groups continue plotting possible attacks in Sri Lanka,” an embassy statement said.

Senior figures called to resign as dozens more detained

Sri Lanka’s Inspector-General of Police, Pujith Jayasundara, said on Friday he would hand in his resignation following criticism authorities did not heed warnings about an imminent attack.

Mr Sirisena called on him to step down earlier this week, along with Defence Secretary Hemasiri Fernando, who resigned on Thursday.

Zahran, who led a group known as the National Thowheeth Jama’ath, blew himself up in one of the five-star hotels that were targeted on Sunday, Mr Sirisena said, citing investigators. He was also responsible for organising attacks on Buddhist statues in central Sri Lanka in December.

A senior army officer said they had closely studied Zahran’s facial features from available videos and compared them with the suicide bomber’s and determined that he had been killed. A DNA test is currently being carried out to confirm this.

Sri Lanka’s health authorities earlier revised down the confirmed number of dead in Sunday’s blasts to 253 after police previously said 359 people had died.

– with AAP