A 4-year-old boy was walking with his mother in shallow waters on a beach in Kitty Hawk, N.C., on Wednesday afternoon when a wave came crashing onto shore with ferocity.

The current knocked the family off their feet, ripping the young boy away from his mother and carrying him out to sea. Scouring the water for her son as another wave rushed in, the mother “lost sight of him in the surf,” U.S. Coast Guard officials said. He was gone.

At about 4 p.m., Coast Guard, police and fire authorities launched a search for the missing boy, who had reportedly been visiting with his family on vacation from their home in Manchester, N.H., police officials told the New Hampshire Union Leader.

It was a warm and sunny spring afternoon on the Outer Banks, but the surf was intense, with waves 4 to 6 feet high. The mother and son were walking alone when they were knocked down.

The rescue crews searched a total of 130 square nautical miles, deploying a Jawhawk helicopter and 47-foot motor lifeboat to scan the waters for the boy, according to a Coast Guard news release. But the only sign of the child was his hat, found about two miles north of where he was swept away, about an hour after he vanished, according to 13 News Now.

Coast Guard boat searching for lost N.H. 4-year-old who was swept out to sea at Kitty Hawk, N.C. Video capture from 13newsnow.com

By 8:30 p.m., the Coast Guard had suspended its search.

“Suspending a search for anyone, let alone a young child, is the most difficult thing a commanding officer in the Coast Guard is called upon to do,” Capt. Bion Stewart, a commander of the North Carolina sector said in a statement. “I can’t imagine what the family of this little boy is going through right now.”

“A tragic accident occurred today in Kitty Hawk,” Chief Joel C. Johnson, of the Kitty Hawk Police Department, wrote in a Facebook post, explaining that the boy was swept away to sea under “the watchful eye of the attending parents while walking along the shore.”

“As parents, this is our worst nightmare, even for those of us who love and have grown up by the ocean,” Johnson added. “Please join us in thought and prayer for this family as we mourn with them the loss and give thanks for the well-being of our own children.”

The news of the boy’s disappearance stunned residents and officials in this Outer Banks community, prompting locals to gather at the beach to join the search. One man hovered over the waters in his powered paraglider for two hours in the hopes of finding the boy.

Johnson wrote on Facebook that police received a “large number of offers from all over” to assist in rescue efforts and support the search crews.

“Due to wind, currents and other environmental conditions we cannot pinpoint a specific area for searching,” he wrote. “If you or a group would like to search you are more than welcome.”

But on Thursday morning, Johnson wrote that all efforts were “on recovery to offer this family closure.”

“If you happen upon something at the beach that requires a closer inspection by authorities please limit your communication to 911,” he wrote. “Continued well wishes and calls for peace are welcomed. We will pass all of them along to the family. Please continue to join us in thought and prayer as we mourn with them this tragic loss.”

The family has not been identified, but police told the Union Leader that the boy was the family’s only child.

On Thursday morning, a small group of local residents gathered at the beach, arranging shells in the sand in the shape of a heart. It became an impromptu memorial that grew throughout the day as more locals stopped by to pay their respects to the family. “I just wanted to reach out in some way to the parents,” Mary St. Claire Dunstan told reporter Sam Walker, of the Outer Banks Voice. “My heart is breaking for them.”

“This is probably one of the toughest mornings we’ve had around here in a while,” Walker, the reporter, said.

By night fall, the memorial had swelled to include crosses, balloons, flowers, lights, teddy bears and a time capsule with notes inside. People stopped by to write messages on shells in black marker. “God bless this family,” one message said. “Please wrap your arms around them.”

Jeremy Thomas, chief petty officer with the U.S. Coast Guard in Wilmington, could not say how frequently people are swept up by currents while walking in shallow water. But “we know that the rip currents in North Carolina are bad,” he told The Washington Post late Thursday night.

“It’s always a danger near the ocean,” Thomas said. “It’s just a tragic case. No one wants to see something like this happen.”