A standoff between an armed man and dozens of police officers at a house in Trenton continued into a second day, the police said on Saturday, amid reports that the man had killed at least one person inside the home and was holding children hostage.

The authorities first went to the home, on Grand Street near the Delaware River, on Friday afternoon for a scheduled visit “to check on the well-being of an individual,” according to Sgt. Robert Carrier, a spokesman for the Trenton Police Department.

That visit led to the discovery, Sergeant Carrier said, that at least one person in the house was dead and that others were being held by an armed man. The police evacuated nearby homes.

The Federal Bureau of Investigation had provided agents to assist in the case, Sergeant Carrier said. He declined to give the names or ages of the people in the house or to provide further details.