Nassau County authorities on Thursday responded to a bomb threat at the house of the judge presiding over the civil fraud trial of Donald J. Trump.

A spokesman for the Nassau County police department confirmed that there was an investigation at the house of the judge, Arthur F. Engoron, who in several hours is expected to hear closing arguments in Mr. Trump’s case. Two people with knowledge of the matter said that the threat involved a bomb and that the bomb squad came to the house.

It was not clear whether the threat would delay the proceedings.

The threat came the morning after Mr. Trump again attacked Justice Engoron on Truth Social, his social media site, saying that the judge and the New York attorney general, who brought the fraud case, were trying to “screw me.” And it came just days after the police in Washington were called to the home of the federal judge overseeing Mr. Trump’s election interference case.

Mr. Trump originally planned to speak in his own defense at closing arguments Thursday. But Justice Engoron said he would have to abide by rules that apply to lawyers giving closing arguments and refrain from delivering a “campaign speech.”

A lawyer for Mr. Trump, Christopher M. Kise, said that the conditions were untenable, and, after unsuccessfully requesting a delay because of his mother-in-law’s death, Mr. Trump appeared to back down from speaking.