The blaze broke out around 4 a.m. at Perretti Farms, claiming 12 mares and 12 foals, WCBS-TV and WCBS Radio in New York reported, citing the Monmouth County prosecutor's office.
The receiving barn was filled to capacity -- a dozen stalls with 12 mares and their foals -- when the fire started. The 24 horses never had a chance to escape as their stable burned to the ground, reports WCBS-TV correspondent Magee Hickey.
An arson squad and state police were investigating the cause of the blaze.
Perretti Farms, which bills itself as the state's largest horse farm, specializes in the breeding and racing of standardbred horses. It has 200 mares and six stallions on 900 acres.
According to Anthony Perretti, son of the farm's founder, William Perretti, "It was very upsetting. We started the farm with no money. It was a potato farm, a vegetable farm. And he built everything you see here, and this is kind of [my father's] baby, his dream."
The animals reportedly died quickly from smoke inhalation as their stable burned stable burned into a charred skeleton.
"It's sickening just to think of them being trapped. Cause the thing about horses in barns is they are locked in and can't get out," said Nicola Abrams, one of the horse-trainer's wives.
Abrams, whose husband trains horses at Perretti Farms, still doesn't know if any one his prize mares are among the dead.
The fire came 10 days after at least three horses perished in a Hunterdon County barn fire at the Black River Farm in East Amwell Township, about 25 miles northwest of Perretti Farms.
State police said an electrical problem sparked the fire, saying electricity that powers heaters that keep water in troughs from freezing ignited a stall at Perretti Farms around 4 a.m. Friday morning.
Hay and varnish quickly fueled the flames.
A worker at the farm says the horses were worth nearly $1.5 million.
Perretti Farms is the largest horse farm in New Jersey for the breeding and racing of standard breds, with more than 900 acres in all. The farm was founded in the late 1980s by noted automotive dealer William Perretti, who has been named breeder of the year.