The Selsey Coastguard was called to West Wittering beach twice this afternoon to reports of missing children, a spokesman said.
The first call came at 2.05pm when the team was paged to reports of a missing five-year-old at the beach.
The team arrived to further reports that a member of the public had found a child matching the same description walking along the beach in East Wittering, the spokesman said.
Coastguard Rescue Officers met up with them and brought the child back to West Wittering Beach to reunite them with their parents.
The spokesman said: “Thank you to the of the family that found the child and brought them to us.”
Later today at 3.20pm, the team was called to reports of two 13-year-olds missing at the beach.
As search teams were commencing their searches, the two children were found safe and well and the team was stood down, the spokesman said.
The Coastguard spokesman said: “Thank you to the West Wittering Lifeguards for their amazing support as always, and for starting the season early (instead of starting at the end of May) due to the predicted nice weather that has been forecast over Easter.
“Free child safe wristbands are available at West Wittering lifeguard tower.
“If you have children and are visiting the beach, please use them, put your contact number on them.
“Make sure your children wear them and keep an eye on your children at all times.
“In an emergency out at sea, on the beach, or along the coast dial 999 and ask for the Coastguard.”