Late Wednesday, New Jersey officials announced the state’s first case of the coronavirus, a man in his 30s who had been hospitalized since Tuesday in Bergen County, just across the Hudson River from New York City.

Gov. Philip D. Murphy said in a statement that the state’s Department of Health had gotten a “presumptive positive result” from a sample that was being submitted to the federal Centers for Disease Control and Prevention for further confirmation. No information was provided about how the man might have become infected with the virus.

The nine new cases in New York on Wednesday included the Westchester man’s wife; his son, a 20-year-old college student in Manhattan; his daughter, 14; and a neighbor who drove the man to the hospital.

A friend of the man who spent time “in close proximity” with him also tested positive for the virus, as did that friend’s wife and three of their children, Mr. Cuomo said.

Officials said they were still uncertain how the man, 50, who had not been to any areas with widespread transmission of the virus, had become infected. He became ill on Feb. 22 and was admitted to NewYork-Presbyterian Lawrence Hospital in Bronxville, N.Y., five days later.