A callous crook robbed a 10-year-old boy of $8 as the child and his younger sister walked down a Brooklyn street after a trip to Brooklyn pizza spot, police said Saturday.

Victim Alex Medina and his sister, age 7, were walking side-by-side down Sterling Place near Utica Ave. in Crown Heights about 11 a.m. Friday when the mugger, who is believed to be homeless, stormed up and snatched the cash right out of the child’s hand, police said.

The thief had confronted Medina moments earlier, asking for some money, the child recalled.

“He asked me if I can give him $5 dollars but I ignored him and walked away,” Alex told the Daily News Saturday. “The second time I went to the pizzeria, he came, grabbed my hand and took the money and just ran off.”

A neighbor of Alex and his mother, Ana Garcia, caught the robbery on a surveillance camera.

“It looks like two children were coming down the block, a boy and girl. Someone behind them is calling out to them,” the man, who wished not to be named, told The News. “The guy comes up and puts his hand in their bag and seems like he grabs something.

“You get packages stolen sometimes, but don’t see anyone robbing others around here,” the neighbor said.

Alex had already gone to Crown Fried Chicken and Pizza around the corner from his home to pick up an order earlier in the day, but he had forgotten to pick up one item.

He had just returned to the store to grab the extra food and was returning home with his sister in tow when the thief jumped them.

“He grabbed me by my right hand and took the money out of my left hand. I had like $8 dollars,” the child recalled. “It was my sister that was with me but there wasn’t many adults around to help. I got scared. I didn’t know what he was going to do.”

The thief ran off toward Utica Ave.and Lincoln Place and disappeared, cops said. He remained at large Saturday.

“I had never seen him before,” Alex said.

Neither child was harmed, cops said.

Alex called police and reported the robbery. A short time later, he and his father drove around the neighborhood and found the thief nearby.

“(My dad) went up to him and said, ‘Did you steal money from my kids?’” Alex recalled. “My dad took a picture of him and then the guy took off.”

Police recovered surveillance footage of the thief, who was sporting a white T-shirt, black pants and a backpack at the time of the robbery. He was also holding a pair of sneakers.

Cops released the images Saturday in the hopes someone can identify the thief.

Neighbors were stunned by the cold-hearted crime.

“Who does that to kids? That’s really bad,” asked one area resident, who asked not to be named. “Sometimes you hear about people getting their packages stolen, but (robbing children), that’s evil to do.”

Anyone with information regarding the thief’s whereabouts is urged to call NYPD Crime Stoppers at (800) 577-TIPS. All calls will be kept confidential.