Boston – Police are trying to determine how an 8-year-old boy wandered away unnoticed from a city-run summer camp at a Boston beach and ended up dead, his body found five hours later in the water."This is the worst part of our job. Dealing with a tragic death like this," Boston Police Commissioner William Evans told reporters at a Tuesday evening news conference.Kyzr Willis was last seen around 14:00 on Tuesday near the L Street Bathhouse at Carson Beach in the city's South Boston neighbourhood. Willis was attending a day camp at the Curley Community Centre, which includes the bathhouse, police said."Right away we deployed officers from around the city looking for the young child. We checked the water, we checked the shoreline, we were out in neighbourhoods, we checked the area around his home in Dorchester, Evans said. "We searched the best we could."'Thorough investigation'Police found the boy's body around 19:00. Family and friends, who had rushed to Carson Beach when they heard the child was missing, broke down in tears. It was not immediately clear how the boy slipped away from the camp, which is run by the Boston Centres for Youth and Families."We'll conduct a thorough investigation, but right now, let's all pray for the family. They're going through something that I don't think anyone here wants to go through," Evans said.Boston Mayor Martin J Walsh, who was returning home from the Democratic National Convention in Philadelphia, released a statement on Tuesday night."I will be working closely with Boston Centres for Youth and Families and the Boston Police Department until we know exactly what happened," Walsh said, adding that his thoughts and prayers are with the Willis family.Quincy police, state police and the US Coast Guard all assisted in the search. The bathhouse will remain closed until further notice as police continue to investigate.