St Mark's Church in Kennington was packed on Sunday evening as Christians, civic leaders and concerned members of the local community came together to pray that God would transform London, restore their hope and show them how to reach out to young people caught up in violent crime and gangs.

Julaine Hedman, Head Teacher at St Mark's School in Lambeth, told the congregation to help disaffected young people in the city by becoming people of hope.

"We have to be the people they look at and see hope in for their future," she said. "We have to be the hope in this world."

Present at the evening were many civic leaders including Councillor Liz Atkinson, Mayor of Lambeth, Councillor Mark Bennett, Lambeth Cabinet Leader for Community Safety, and Superintendent Jonathan Trottman of Lambeth Metropolitan Police.

Councillor Bennett said he was "saddened and concerned" by the recent teenage killings in London, which included the killings of 15-year-old Adam Regis, who was stabbed to death near West Ham's Upton Park Stadium in March, and 15-year-old Billy Cox, who was shot dead at his home in Clapham in February.

He added that gang membership had become another form of modern day slavery but warned there would be no quick fix to the violence. Rather, he predicted it would take years and "constant and focused prayers from us all" before London would be rid of the problem.

Rev Les Isaac, founder of Street Pastors, said that working individually would not solve the problem. "But together we can," he said, as he called for a concerted effort from the 'urban trinity' - the church, local government and police - to tackle head-on the problem of violent crime among young people in the capital.

He challenged Christians in particular to do more to help young people escape a life of crime.

"Let's be willing to be obedient and say 'Lord, use me'. Pray that the Lord uses us to bring hope to our young people."

Rev Joel Edwards, the General Director of the Evangelical Alliance, told the church and police in particular not to lose hope in light of the widespread violence but to look to God and a vision for London "bigger than themselves".

"A church beginning to look outward and not inward is a church infused with hope," he said, as he called for politics and the church to become infused with a "theology of hope".

"Hope is the core business of the church," he said.

The evening of prayer was organised by Ascension Trust in conjunction with St Mark's Church. Other Christian leaders present included the Venerable Michael Ipgrave, Archdeacon of Southwark, Rev Katei Kirby, CEO of the African and Caribbean Evangelical Alliance, and Patrick Regan of XLP.