YAMBIO, South Sudan — More than 300 child soldiers were released Wednesday by armed groups in South Sudan, the second-largest such release since the country’s civil war began five years ago. All sides in the conflict have recruited more than 19,000 children as fighters.

The “laying down of the guns” ceremony for 87 girls and 224 boys was the first step in a process that should end with at least 700 child soldiers freed in the coming weeks, the United Nations said.

The United Nations has helped win the release of almost 2,000 child soldiers in the past few years. More than 10 percent of them have been younger than 13.

Human rights groups say child recruitment continues, even as the government says it has committed to ending the practice.