"There's been a shooting."

These chilling words were spoken to Clive Calver, the former director of the Evangelical Alliance, last Friday – a day which started out like any other, and ended in unimaginable tragedy.

Clive now leads Walnut Hill Community Church in Connecticut, and lives in Newtown, where last week a lone gunman killed eight boys, 12 girls and six adult teachers before turning the gun on himself.

"I arrived at the church on Friday morning and one of my staff was standing outside saying: 'There's been a shooting,'" Clive recalls. "We knew that it was at his son's school. So we jumped in the car, praying our way through the 12-minute drive. The call came through that his son was alive."

Clive was the first clergyman on the scene where hundreds of children and parents were milling around with police and fire officers. Having worked as president of World Relief, co-ordinating disaster response during earthquakes, hurricanes and volcanoes, he put his experience to good use, to help bring order to the situation.

"I never dreamed I would have to do this in sleepy Newtown," he said.

The church put its 22 pastors to good use, helping out at the hospital, on the scene and in the town hall, praying and ministering to people where needed.

Describing one of the most chilling scenes, Craig Mowrey - one of the pastors at the church who was at the scene, said: "One by one, children were being found by their parents. It was total chaos. And then you started to get parents asking: 'Where's my child?' Nobody dreamed they were dead."

He added: "Five hours after the shooting, shaking with fear, we approached the first set of state troopers and they let us in to the fire house where parents were waiting. The tension was incredible. Most of them hadn't been watching the news. They were clearly hoping upon hope that their child or family member was one of the ones being treated at the hospital.

"We had an opportunity to pray for folks and minister to them. There was very much the unknown in that moment."

Eventually, Governor Malloy broke the news to those who had been waiting. Craig said: "In that moment, all of them knew that those they were waiting for – they were never going to see them again. There was terror and shock and anger. Some just sat completely comatose. It was a terrible situation. People also found out that they weren't going to be able to recover their children's bodies as it was a crime scene. We helped to usher people out of that room, and most of them did the only thing they could do – go home."

That morning Craig had had breakfast with Will, a member of his congregation – a police officer who was one of the first responders and who saw Adam Lanza kill himself. "He saw things that no man should ever have to see," Craig said. "He was a true hero. More would have been killed that day if it weren't for him."

That night, Walnut Hill Community Church opened its doors to anyone who wanted to come and pray – and more than 500 people did.

This Friday, Clive will hold the funeral of Dylan Hockley (pictured), a six-year-old autistic boy who was killed in the shooting. Dylan's body was found cradled in the arms of his special needs teacher Anne Marie Murphy, who was also killed.

The Hockley family had moved from their home in the UK to Connecticut last year. In a moving statement, they said: "We take great comfort in knowing that Dylan was not alone when he died, but was wrapped in the arms of his amazing aide… Dylan loved Mrs Murphy so much and pointed at her picture on our refrigerator every day.

"Though our hearts break for Dylan, they are also filled with love for these and the other beautiful women who all selflessly died trying to save our children. Our thoughts and prayers are with the other families who have also been affected by this tragedy. We are forever bound together and hope we can support and find solace with each other."

Walnut Hill Community Church is asking the evangelical Church from across the world to donate to a fund to help its heartbroken community, and to provide immediate and long-term counselling services for local residents.

"We know this is not going to be over tomorrow," said Clive. "The world will have forgotten this in a month or two. But we will still be living with it. When you say 'Dunblane', you don't think of Andy Murray, you think of the tragedy that happened there.

"This place that we had hoped would become a byword for a real spiritual renewal will now be a byword for the work of the evil one. We have dreamt of a real move of God in this place and we know that God knows what He's doing."

Clive rejected claims by some Christian groups who have said the tragedy happened because we have taken God out of our schools and out of our society.

But he said: "If God is pushed to the sidelines of a society, then that society will struggle to know what to do when it desperately needs God.

"There is a shadow of grief which has been cast over this town. But I believe that God is sovereign; that He will serve His purposes in this thing. I'm not glib enough to say that this is good news for the kingdom or that it's a sign of the times. The devil just won a battle, but Jesus is going to win the war.

"God had nothing to do with the disaster. But God will have an awful lot to do with the recovery."

For more details of how you can donate to the Walnut Hill Community Church Sandy Hook fund, visit their website.