A friend of the 25-year-old who is accused of shooting and killing one woman and injuring several others at a Tennessee church, has described the suspected gunman as a 'deep Christian believer' who lacked aggression.

Emanuel Samson is accused of pulling into the car park of the Burnette Chapel Church of Christ in Antioch on Sunday morning before opening fire.

A neighbour of the suspect and a friend of six years, 20-year-old Dejuan Martin, said that he was shocked by the shooting, telling ABC News that Samson is 'a normal guy'.

He said: 'I didn't believe it. I never thought he'd do something like this.'

Martin described the alleged killer as passionate, outgoing and a 'pretty warm-hearted' person.

Police have said that the motive is under investigation, and the US Attorney's Office says a federal civil rights investigation has been opened.

Police said Samson had allegedly been to this church — which has racially diverse parishioners — one to two years ago.

Four guns believed to be Samson's were recovered: two at the church and two from his car, police said.

Samson is being charged with one count of murder, with additional charges pending.

Melanie Crow Smith, a 39-year-old a married mother of two, was killed during the attack and Samson – a bodybuilder born in Sudan – was arrested at the scene.

He opened fire at the church on Sunday as the service was ending, having been seen in the car park wearing a neoprene mask. His rampage was brought to an end when a church usher, Robert Engle, tackled him and despite being struck on the head by Samson's pistol forced him to shoot himself in the leg.

Engle then ran to his car, where he had a pistol, and held Samson at gunpoint until police arrived.

Engle downplayed his heroics yesterday.

'I ask everyone to pray for the victims, family members of the victims, our church community. Please pray for healing. Also, please pray for the shooter, the shooter's family and friends. They are hurting as well,' the 22-year-old said in a statement.

'The real heroes are the police, first responders and medical staff and doctors who have helped me and everyone affected,' he added.

But Metro Nashville Police Chief Steve Anderson said: 'He's the hero. He's the person who stopped this madness.'

The church's pastor, Joey Spann, and his wife Peggy were also shot. Church member Minerva Rosa, who applied pressure on Spann's wound, praised Engle, saying: 'He's amazing. Without him I think it could be worse. He was the hero today.'

Meanwhie, funeral services have been arranged to take place tomorrow for Melanie Crow Smith.