The attack is coming on the heels of a similar one in Maiduguri, the Borno State capital on Sunday night, where four people were feared killed in their homes by suspected members of the Boko Haram sect.
Also, some unidentified gunmen Monday attacked a police station in Shagari Local Government Area of Sokoto State.
However, an eyewitness account said members of the Deeper Life Bible Church were attending night service when the gunmen struck.
The eyewitness further stressed that students of the Federal College of Education and motorists travelling across the town either to the Northern or Southern parts of the country had to take cover to avoid the rampaging of the gunmen.
The gunmen were said to have arrived the church in a Toyota Hiace bus and immediately started shooting sporadically as they made their way into the church.
The worshipers, who were caught napping could not escape immediately as the gunmen allegedly blocked the entrance of the church and then opened fire on the worshipers.
Though some worshipers were lucky to have escaped during the attack, which lasted for about 20 minutes, others, however, could not.
When THISDAY called on the Police Public Relations (PRO) Unit, one of the spokesperson, Mr. Ajayi Okasomi, confirmed the attack but said they are still awaiting official report from the Divisional Police Officer in Okene.
Also confirming the attack, the Joint Task Force Commander in the state, Lt Col. Gabriel Olorunyomi, confirmed the attack.
Olorunyomi said 15 worshippers died on the spot while the attack lasted, stressing that another died on the way to the hospital.
The commander said many of the injured persons were rushed to hospitals in Lokoja, a distance of 40 minutes drive from Okene.
He said the casualty figure might rise considering that some of the worshippers sustained serious injuries.
It would be recalled that in the last few weeks there is hardly a day without two or more people being killed in their residences.
The killings, which include the low and mighty, seem to be a change of strategy by the Islamic fundamentalist group.
The new strategy is believed to have been evolved by the group to keep them in the consciousness of the public after they have been prevented from wreaking havoc on military and strategic installations including markets and places of worship by the presence of heavy security.
Meanwhile, the Joint Task Force (JTF) Monday alerted the public of plan by Boko Haram members to undertake massive snatching of vehicles in Maiduguri and its environs, which they would later use for their suicide mission.
The vehicles, according to the task force, would be laden with explosive and used to bomb strategic locations and cause beach of peace in the town and perhaps neighbouring towns.
The statement signed by the task force Field Operations Officer, Col. Victor Ebhaleme, read: "The JTF wishes to alert members of the public of the desperate moves by Boko Haram terrorists to steal and snatch vehicles for suicide bombings."
Ebhaleme in the statement further asked those whose vehicles have been stolen to immediately report such incidents to the nearest police station or to the JTF.
In Sokoto, THISDAY checks revealed that the gunmen arrived the police station on motorcycles when residents of the area were about to break their fasting and engaged the policemen in a gun duel.
It was also gathered that the exchange of gunfire lasted for about one hour after which the gunmen detonated the bomb at the station.
Unconfirmed reports from the area revealed that some policemen on duty were injured.
When contacted, the state Police Public Relations Officer (PPRO), DSP Sani Sanusi, declined to comment on the attacks.
He maintained that the state Commissioner of Police had mandated him not to comment on the issue until today.
"Please I am not in a position to confirm the incident to you because my boss has mandated me not to say anything till tomorrow," Sanusi said.
Meanwhile, President of the Senate, Senator David Mark, Monday lamented the killing of six soldiers and two police officers serving with JTF in Damaturu, Yobe State.
The eight security personnel lost their lives at the weekend when a suicide bomber riding on a Sports Utility Vehicles (SUV) rammed into them at a security post.
Mark described their death as shocking and commiserated with the Chief of Army Staff, Lt. Gen. Azubuike Ihejirika, and the Inspector General of Police (IG), Mr Mohammed Abubakar, on the loss.
He also expressed condolences to the Government and people of Yobe State as well as the families of the officers and men who died in the attack.