Special Agent Samuel Hicks, who was taking part in a drug-ring roundup, was shot around 6 a.m. in Indiana Township, a middle-class community about 10 miles northeast of Pittsburgh.
The home's owner, Robert Korbe, was in federal custody in connection with the shooting, said a person familiar with the investigation who spoke on condition of anonymity pending an official announcement.
Hicks, 33, had been with the FBI since March 2007, and was assigned to the Pittsburgh office in August 2007, said Michael Rodriguez, special agent in charge of the Pittsburgh FBI office. A former Baltimore police officer and school teacher, Hicks graduated from Southmoreland High School in Alverton and from the University of Pittsburgh-Johnstown with a degree in chemistry in 1999. He leaves behind a wife, Brooke, and a 3-year-old son.
"Special Agent Hicks made the ultimate sacrifice that any law enforcement officer makes for his country," Rodriguez said in a statement read to reporters. "He served with honor and bravery and will be greatly missed by his colleagues here in Pittsburgh and throughout the FBI."
Korbe was expected to appear in federal court later Wednesday. He was one of 35 people charged in a 27-count drug-trafficking indictment unsealed Wednesday. The indictment accuses the defendants of conspiring to traffic cocaine and crack from October 2007 through September.
At the federal courthouse in Pittsburgh, public defenders were in a courtroom Wednesday morning awaiting the arrival of those rounded up in the drug sweep.
A woman who answered the phone at Hicks' home said Brooke Hicks was not taking calls.
FBI Director Robert S. Mueller III said: "The loss of Sam Hicks is a tragedy. Our hearts and prayers go out to Sam's family and the members of the Pittsburgh field office."
Korbe, 39, has a criminal record. In 1993, he pleaded guilty to several drug charges and a firearms count and was given probation, according to online court records.
In May, he was arrested on charges of aggravated assault, recklessly endangering another person, resisting arrest and drug counts, according to online court documents. Sumner Parker, Korbe's attorney in that pending case, did not immediately return a message left by The Associated Press.
The home, a cream-colored house that backs up to fields and woods, is owned by Korbe, according to online county records. A child's basketball net and play fort could be seen in the backyard. Authorities remained on the scene Wednesday morning, blocking the street to the public. Several police cars, including unmarked cars, lined the street.
No one answered the door at the home of Korbe's parents, about a half mile away. On the front door, a small magnetic red, white and blue flag sticker read "Honor America's fallen officers."
A neighbor, retired chemistry teacher Gregg Caldwell, said he believed Korbe was in the car-detailing business. Korbe had two children of his own, Caldwell said.
"He seemed like a pretty good kid," Caldwell said. "It's just not something we see going on here in Indiana Township."
Emergency dispatchers had initially said the victim was a police officer shot in a home invasion.
CBS station KDKA reports that Hicks is the only FBI agent assigned to the Pittsburgh office who has died in the line of duty there. Only 34 agents have died in hostile situations in the 100-year-history of the agency, KDKA reports.
The last FBI special agent killed in the line of duty was Barry Lee Bush, who was accidentally shot and killed by a fellow agent outside a bank on April 5, 2007, in Readington, N.J., according to the FBI. Bush, 52, of Forks Township, Pa., and other agents were in pursuit of three bank robbers who were armed but did not fire their weapons, authorities said.