RANCHO SANTA MARGARITA (CBSLA.com) — A 4-year-old boy’s first time to the beach was a memorable one, but not in a good way.

Liam Brenes’ family took him to Crystal Cove State Beach Sunday morning. They left their belongings, including the boy’s prosthetic leg, on the beach while everyone went to look at tide pools. Liam put on an old leg to go to the water.

When they returned, Liam’s new prosthetic leg was gone. “They took my clothes, my shoes and my prosthetic leg,” Liam said.

“I feel bad for him because his leg was stolen, and the people who stole it probably didn’t even think twice about that, like didn’t even care something important was in there,” said brother Aiden.

Their dad, Frank, rummaged through nearby trash cans, dumpsters and bushes hoping someone had tossed it away, but no luck.

“I’m angry, kind of mixed emotions. I’m angry and sad: angry at the people who did this and sad for Liam,” said brother Connor.

Liam’s mother, Amanda McFarland, has been spreading the news on Facebook. “I’m not sure why you would take that at all. It’s a child’s leg,” she said.

Born without a fibula bone, Liam had part of his leg amputated when he was 1 year old. He said he will ask for a new prosthetic leg for Christmas.

Aiden is pleading for the thief to return his brother’s leg. “If you have a chance, can you at least give us back the leg and glasses?”