The postholiday Sunday was intended to be fun for a few young friends in Franklin Township - a day that included a trip to the mall, a pizza dinner, and the delight of perusing neighborhood Christmas lights.

But as thoughts turned to a planned sleepover, and the three young boys opted to walk the short distance to the Delsea Drive house where two of them lived, the weekend became defined by tragedy.

As the boys crossed Delsea near Elmer Street, officials said, one of them, Matthew McCloskey, 10, was fatally struck by a northbound police cruiser on the heavily traveled Route 47. The officer was responding to a police call for assistance, officials said.

Matthew, a fifth grader at the nearby Caroline L. Reutter School, was pronounced dead at 7:04 p.m., authorities said. An autopsy Monday determined that he died of multiple injuries, officials said. The manner of death was listed as accidental.

The two other boys, who are brothers, were not injured. Their parents had been following the group in a car back to their house on Delsea.

"We were all heading home," the father of the two boys, who declined to talk further, said outside his home, which fronts the southbound lane.

"The boys said, 'We want to walk home,' " a relative of the father of the young brothers said. "They've done it a million times."

Authorities identified the officer as Nicholas Locilento, 23, who has been placed on paid administrative leave.

The biggest question investigators face is whether Locilento had his lights or sirens on when his cruiser struck Matthew.

"I know that there were people who told reporters yesterday that the lights were not on," said Bernie Weisenfeld, a spokesman for the Gloucester County Prosecutor's Office. "So [investigators] focused on that."

"I just don't know what answer they had," he said Monday night.

Weisenfeld also said he did not know what type of call police had asked Locilento to assist, or the cruiser's speed. The speed limit on that stretch of Delsea is 50 m.p.h.

Locilento became a full-time patrolman Nov. 25, when he was promoted from Class II special officer. He joined the force in that role in June 2013. A Class II officer has powers similar to a patrol officer but may not be able to carry a service weapon off-duty, Weisenfeld said.

Locilento was taken to a hospital after Sunday's accident as a precaution but was not injured. On Monday, no one answered the door at a Pennsauken home that, according to public records, belongs to his family.

A statement Sunday evening on behalf of Franklin Township, provided by the town administrator, said, "Our thoughts and prayers go out to the McCloskey family, that tragically lost their son. Whenever a young life is lost like this it is tragic for everyone, his family and our community.

"While this is very difficult for the young boy's family, it is also very difficult for that police officer involved. It is our understanding that the officer was responding to an urgent call when this accident happened and we support the officer who was involved in this. He is very shaken up by being involved in this incident and we are supporting him in this difficult time."

A memorial outside the house where Matthew was going continued to grow Monday afternoon, as candles burned into the early evening. A Spider-Man balloon and a foam football had been left. Beside a photo of Matthew, taken Sunday at dinner, were the words: "You are a light to our world."

Matthew had aspirations of becoming a police officer and even attended a police camp last summer, according to a memorial fund-raising page set up on by family friends.

The boy lived on Elmer, near the end of a cul-de-sac, in a home with a towering basketball hoop by the driveway. Neighbors estimated that he and his family - three older siblings and his mother, Michelle - had lived in the house a little more than a year. A woman at the house said Monday afternoon that the family was not prepared to comment.

"It's a tragedy," said David Parent, 52, a neighbor.

"He always waved, smiled," Parent added. "They played basketball all summer."

"Our hearts just bleed for this family," Franklin School District Superintendent Troy Walton said. "We just can't imagine; it's an absolute tragedy."

Reutter School principal Theodore Peters said he had spoken with several of Matthew's teachers. "I think everyone at this point is in shock," Peters said. "They describe him as a very mature young man, who really was a model student within his classes."

Matthew also played baseball on the Orioles, a team of 10- and 11-year-olds in the Franklin Township Little League. Thomas Schofield, league president, recalled Monday that his son's team, the Blue Jays, played Matthew's squad several times in the spring.

Schofield, also a volunteer firefighter, responded Sunday night to the accident, where he said the mood was "just quiet." Later, at the Franklinville Fire Company, a somber silence overtook the normally chatty responders.

"Any time there's a child involved, it's harder on everybody," he said, expressing sympathy for both Matthew's and the officer's families. "It was just a heartbreaking loss for our whole community."

Reutter will have grief counselors available for students and families Wednesday from 9 to 11:30 a.m., as well as when school resumes Monday.