A dragnet of federal, state and local law enforcement is on the hunt for the gunman who fatally shot a federal court judge’s son and wounded her husband – all while disguised as a FedEx worker – at their New Jersey home Sunday night, officials announced Monday.

U.S. District Judge Esther Salas’ son, 20-year-old Daniel Anderl, was killed and her husband, defense lawyer Mark Anderl, 63, is in the hospital after the men were shot in the doorway of their North Brunswick home around 5 p.m. Sunday, officials have said.

Salas was in the basement at the time and wasn’t injured, according to the Associated Press. Daniel, a college student, was her only child, officials said.

The young Aldern, who previously attended St. Joseph High School in Metuchen, N.J., was remembered as "a true friend, a proud Falcon, and an overall wonderful human being," according to a statement on the school's website.

"It is with the utmost sadness that we inform you that Dan Anderl '18 was taken from us last night," the statement reads. "He will be truly missed. We pray for Dan's family and friends during this unbelievably difficult time – please know, we are mourning with you."

North Brunswick Mayor Francis “Mac” Womack told NJ.com Mark Anderl needed surgery shortly after the attack, but is now in stable condition at an area hospital.

The FBI is investigating the case with the assistance of the U.S. Marshal Service, the Bureau of Alcohol, Tobacco, Firearms and Explosives and state and local agencies, according to a series of tweets.

The suspect, who was not in custody as of Monday morning, is believed to have acted alone, posing as a FedEx delivery person.