Anguished family members and hundreds of volunteers have launched a massive search for a missing Hasidic boy who vanished on his way home from a Brooklyn day camp on Monday.

Leiby Kletzky, 9, was last spotted leaving the Boyan Day Camp on 44th Street near 12th Avenue at 4:50 p.m., police said.

He was supposed to meet his mother on 13th Avenue and 50th Street but mysteriously failed to show up.

"Volunteers have been out there all night searching backyards, front yards, anywhere where a child could possibly be" said Assemblyman Dov Hikind (D-Brooklyn).

Buses loaded with volunteers have come from New Jersey to aid in the search.

"Usually, these things are solved in a few hours," said Jacob Daskal, a member of the Shomrin volunteer civilian patrol. "It might be an abduction, but we're still hoping it's not."

Daskal said the boy was caught on surveillance camera leaving the school. He walked eight blocks to meet his mother. He disappeared during that short walk.

Boro Park Shomrim chief Simcha Bernath said the family confirmed the boy walked by himself, but normally he took the bus. He was supposed to walk from 12th and 44th to 13th and 50th.

"Because they had an appointment, they decided he could meet them," he said. "Everybody knew it was OK to walk by himself. But his regular routine was to go on the bus and go home."

"They're distraught. They can't figure out what happened," Bernath added.

Hikind's office, along with the boy's family and friends, is offering a $100,000 reward for any information on his whereabouts.

"It's quite amazing. Money's just coming in from people who just want to express their concern and want to do something,'' Hikind said.

"The amount has grown on the part of business people throughout the community. We started out this morning with just $5,000," Hikind said.

"We're hoping for a good outcome but this is becoming very scary," Hikind said.

Kletzky, the second youngest of five kids, was last seen wearing a blue shirt with green and white stripes, blue pants and black sneakers.