Unknown gunmen on a motorbike on Sunday shot dead an official at a church in Mombasa in an attack.

Regional CID boss Henry Ondiek said the deceased George Mureki, secretary at the Maximum Revival Centre in Majengo, was accosted and shot dead from behind by the assailants within the church compound who were armed with firearms.

"We are pursuing the gunmen," he said.

According to investigators, the assailants had targeted worshippers but were repulsed by two police officers who were manning the church that is situated at Mvita primary school.

"He was shot as he was about to enter into the church, but immediately our officers responded and engaged them in a shootout and they escaped," said Ondiek.

"It's very sad incident now that we had managed to return calm to Mombasa, this should be treated as isolated incident. We have launched investigation to establish the motive of the attackers." said Ondeik.

Witnesses said the gang rode off soon after the shooting that happened as the church congregation was in session at an open field at a primary school. The official is said to have been shot as he walked in.

The motive of the attack is yet to be known, but officials say they suspect it could be part of a wider terror network in the area.

"They shot at the secretary killing him. We suspect these are terror elements operating here," said an officer who asked not to be named.

Sympathizers of Al-Shabaab terror group operate freely in Mombasa and have in the past threatened to kill pastors as revenge to the killing of their Sheikhs.

The church had a capacity of more than 70 worshipers who were attending the Sunday service. The National Intelligence Service has warned of more attacks by homegrown terror groups across the country.

The groups have been blamed for the killing of moderate Muslims and perceived state informers in Mombasa County.

Meanwhile, church leaders in Mombasa have condemned the killing of the church official. Anglican Church of Kenya Bishop Boniface Kalu said the government should pursue the killers and brought them to book.

He called for protection of all church leaders especially in Mombasa where unknown assailants have been targeting churches and Christians.

"As we condemn this heinous act we are at the same time asking the government to provide protection to churches and their leaders because they have become targets by criminals," he said.