At least six people have died after gunmen opened fire on the congregation of Joy Jesus Church in the Likoni area of the Kenyan port city of Mombasa.

The attack happened at 10:30am on Sunday. The men were reported to be armed with AK-47s and pistols. Two entered the church and started firing, while at least one more stood outside the church's exit, waiting for fleeing parishioners.

Eyewitness Margaret Mwangi told Reuters: "Two people wearing masks entered the church and then started spraying bullets at us."

Peter Muasya also shared what he saw with Reuters: "They were ordinary looking guys, one of them tall, dark and wearing a long-sleeved shirt. They walked casually as if all was ok.

"Then they started shooting at those of us who were standing outside."

One survivor, Benson Okoth, told of how he escaped being shot by falling to the floor and pretending to be dead.

Speaking to the Daily Nation, he said: "This is what saved my life. Some worshippers screamed as others fell down on the floor to avoid being shot."

After the attack, blood soaked Bibles and overturned chairs were scattered across the church floor.

Local police chief Robert Mureithi, said in the Guardian that the gunmen "shot indiscriminately at worshippers and then fled".

Two of the worshippers there that morning died immediately, while four others later succumbed to their injuries in hospital. Fifteen more are still receiving treatment, including one infant with gunshots to the head.

Bernard Mweru, the chief administrator of the Coast Referral hospital, spoke about the infant's condition to Kenya's Standard Media: "The infant still has bullets in his head but in stable condition, he might be flown out to Nairobi for further treatment."

There has not yet been any claim of responsibility, but there has been recent criticism of the government by Islamic figures as reports emerge that several senior Islamic leaders have been shot and killed on the Kenyan coast.

Their supporters claim this is the work of the police conducting state-sponsored assassinations, something Kenyan security forces deny.

Kenyan military forces invaded Somalia in 2011 as part of an African Union mission to attempt to overpower the Islamic militant group Al-Shabaab. Fresh Kenyan offensives against the militants began earlier this month. There are groups within Kenya, such as the al-Hijra group, formerly known as the Muslim Youth Center, with links to Al-Shabaab.

Daniel Sinclair, Communications Director at Christian Solidarity Worldwide, said, "The dangerous elements targeting the Christian community also represent a threat to security and rule of law in the country, which affects every citizen. We urge the Kenyan government to ensure that churches in Mombasa are adequately protected.

"We also urge the government to act swiftly to bring the gunmen to justice and deal robustly with the militant elements who are not only determined to deny the full enjoyment of freedom of religion to local Christians, but who also endanger the peace and security of the nation."

This attack comes six months after four gunmen attacked the Westgate shopping centre in Nairobi, which left 63 people dead.

The gunmen in this latest attack escaped on foot before the police arrived. They fled in the direction of Shonda village, and there are reports that they dropped a large bag of bullets while they fled.

Security in the area had been increased recently, after an incident last week where police arrested two people who they reported had a large number of pipe bombs hidden in their car. Experts said the explosives were both numerous and powerful enough to level a tall building.

Kenyan security officials quoted in the Guardian had given warnings of "increased threats of radicalisation" earlier last month.

In February, police raided a Mombasa mosque accused of preaching extremism. Several suspects were detained at what was believed to be a radicalisation meeting.

Kenyan interior minister, Joseph Ole Lenku, spoke on the subject on the Saturday before the attack. The Guardian quoted him saying: "Our officers are out there, they are doing everything possible to fight crime and terrorism."

So far 100 suspects have been arrested, but police chief Mureithi said in the Daily Nation that the "main culprits are still at large".

Mombasa county commissioner Nelson Marwa has announced a major operation involving security forces and the police to better respond to threats of this kind. Speaking to the Daily Nation, he said: "The government will not relent in this fight."