The Akwa Ibom state governor made the announcement via his Twitter account on December 10, 2016.
"I declare Sunday, December 11 and Monday, December 12 2016 as days of mourning in AkwaIbom #Udom Emmanuel", he wrote.
Governor Udom was present at the building collapse, which has killed over 200 people and left a lot of victims.
"I was present at the church during the incident and shared in the agony of the moment. Thereafter, I personally supervised rescue operations and evacuation of the injured to the hospital. I directed all emergency agencies of government especially the construction companies to be involved in rescuing people," he tweeted after the incident.
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Punch reports that a lot of people were seriously wounded or killed, including an aide, a security officer, many dignitaries.
The Secretary to the State Government, Etekamba Umoren, and the Chief Press Secretary to the Governor, Ekerette Udoh, sustained serious injuries.
An eyewitness named Uduak Effiong, a student of the University of Uyo, Department of Communication Arts, revealed details of the incident.
"I saw over 100 dead bodies. These were the ones close to me. From my estimation, more than 300 people might have died as people came from other churches in all parts of the state, including government-sponsored praised singers with uniforms to attend the programme. For some of us that escaped, we only did by the special grace of God," she said.
According to the Chief Medical Director of the University of Uyo Teaching Hospital, Prof. Etete Peters, the state is struggling with the aftermath of the collapse.
"We only lost one person in the hospital except those that were brought dead. In circumstances like this, we have been overwhelmed. We need help from government.
Many victims are in private hospitals and mortuaries scattered all over Uyo metropolis; we can’t really tell how many people have died so far. We have over 200 persons in the mortuaries. We do not have space as people are still being brought in.
We have done our best to revive some victims. Right now, we have over 50 cases we are attending to. This is the first time we are witnessing such an incident," he said.
A lot of people have offered their condolences including the president.
On December 10, 2016, Muhammadu Buhari wrote, "this evening I spoke with Gov. Udom Emmanuel to commiserate with him on the tragic collapse of the Reigners Bible Church in Uyo.
I asked the governor to convey to the people of Akwa Ibom state the deep sorrow felt by me, and by the entire country over this tragedy.
I pray that the souls of the deceased will rest in peace, and that the injured will experience quick recovery.Any tragedy that affects any part of Nigeria affects all of us. Our thoughts and prayers continue to be with the people of Akwa Ibom.”
This condolence message was made via his twitter handle.
Former Akwa Ibom State Governor, Senator Godswill Akpabio, has paid a visit to the victims at the Ibom International Specialist Hospital.
"I was impressed by the efforts of the medical personnel at the hospital. I pray for the quick recovery of the sick and injured," he said.
Governor Udom, dignitaries and a lot of people were at the church for the Archbishopric ordination of its founder, Akan Weeks as Bishop, when the incident took place.