More than 20 horses were killed in Lafayette Township, N.J., when a predawn fire engulfed the barn they were stabled in on Saturday, the New Jersey State Police said.

The horses, mostly show horses that were boarded at the stable by private owners, died inside an indoor arena with a tin roof and walls where their stalls were located, said Arthur Hahn, who owns the farm, Heritage Acres, about 55 miles northwest of New York City. A woman, whom Mr. Hahn said he did not recognize, banged on his door at about 1:30 a.m. to tell him the building, which is across the street from his house, was burning. The cause of the fire was not yet known, the police said.

“The barn was ablaze; it was all on fire,” Mr. Hahn said. At about 4:30 p.m. Friday, Mr. Hahn said, he fed the animals dinner and shut the barn doors tightly to keep the horses warm on what was to be a snowy evening. Those metal doors were too hot to pry open when the fire raged hours later. “You couldn’t even get near it,” he said. “It would burn your hands off.”

“I would rather had my house burned down,” Mr. Hahn said. “The house we could have got out. The barn, the horses couldn’t get out, especially at night. If it was daytime they would have been all out in the pastures. In the night you put them all in so they wouldn’t be cold.”