Ms Salas, who was in the basement of the home at the time of the attack, was not injured.
The FBI issued a statement on Twitter saying it was looking for one suspect in relation to the shootings.
“We are looking for one subject,” said the FBI. “We are working closely with our state and local partners and will provide additional updates when available.”
A gunman has shot and killed the son of US District Court judge Esther Salas during an attack on her New Jersey home, officials say.
The attacker shot the 20-year-old, Daniel Anderl, as he answered the door at the family’s North Brunswick home on Sunday.
Ms Salas’s husband, Mark Anderl, was also wounded in the attack, Chief District judge Freda Wolfson told the Associated Press.
The gunman was believed to have been dressed as a FedEx delivery person, said officials, when he shot Daniel Anderl, a college student and the judge’s only child.
Ms Salas served as a US magistrate judge in New Jersey before she was nominated to her Newark seat in 2011 by former president Barack Obama.
She was also recently assigned to an ongoing case brought by Deutsche Bank investors against the company over alleged money laundering activities involving customers that included the convicted sex offender Jeffrey Epstein.
Democratic New Jersey senator Bob Menendez, who backed Ms Salas’s nomination to the federal bench in 2011, said in a statement on Sunday night: “My prayers are with Judge Salas and her family, and that those responsible for this horrendous act are swiftly apprehended and brought to justice.”
Democratic New Jersey governor Phil Murphy called the shooting “a senseless act” in a statement on Sunday night.
“This tragedy is our latest reminder that gun violence remains a crisis in our country and that our work to make every community safer isn’t done,” said the governor.
The FBI has appealed for anyone with information to come forward.