BOSTON -- Mayor Marty Walsh said Wednesday that his heart breaks for the family of the little boy found dead in the waters off Carson Beach in Boston on Tuesday night.

"My heart goes out to the family, it breaks for the family," said Walsh. "I just can't imagine the sadness, the anger, what they have today in their hearts."

The body of the 7-year-old Kyzr Willis was found about five hours after he was reported missing in the area of the M Street Bath House, reports CBS Boston. He was participating in a summer program run by the city that includes about 100 children.

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Kyzr was last seen out of the water and on the sand. He was supposed to make his way to the bath house to change, but never showed up. State Police said K-9 units, State Police air and sea units, Coast Guard air units, and the Boston Police marine unit were involved in the search.

As the investigation into what happened during the final hours of the boy's life continued Wednesday, Walsh said he planned to meet with the boy's family.

Walsh said the camp had been moved to other sites for the day, and said children that were at the camp Tuesday, as well as the camp's counselors, were talking to grief counselors.

The mayor said he never anticipated a situation where someone that goes to a day camp doesn't go home to their parents.

"We run a great program," Walsh said. "We have not had any type of incidents like this ever before."

But questions about what happened Tuesday lingered, including those about camp protocols and staffing.

Walsh could not speak to the details of the active investigation, but said that it was difficult due to the fact that there were no surveillance cameras along William J. Day Boulevard. CBS Boston has learned there are surveillance cameras on the L Street side of the facility, but not the state-owned side.

Boston Police Commissioner Bill Evans also spoke about the search and it's tragic ending.

"People always ask me about my job, and what's the worst thing you ever do," said Evans. "What we had to do last night was clearly the worst part of my job."

He said initial information led investigators to believe Willis went outside the building, and that's why their search concentrated toward his house.

"From when we got that call, we worked our best to try to find that poor child," said Evans. "I can't say enough about how my officers tried. It was quite an effort by everyone."

The community center that hosted the camp was closed for the remainder of the day Wednesday, but officials said it may re-open Thursday.

"Growing up here, this is where I spent my childhood, playing handball and whatnot," said Evans. "It's a great community center, and hopefully we'll get through this and have the center open so the kids can go back to enjoying it."

Walsh left the Democratic National Convention in Philadelphia early because of the boy's tragic death.

"I got the word that there was a young boy missing. I did not take part in any of the activities yesterday in Philadelphia," said Walsh. "My place is to be here in the City of Boston to support whoever needs to be supported, the family in particular."