Suwanee, Georgia (CNN) -- A gunman in apparent financial distress took several firefighters hostage Wednesday in suburban Atlanta, then was killed in an exchange of gunfire hours later after law enforcement authorities determined he might lash out at his captives.
"It got to the point where we believed that (the firefighters') lives were in immediate danger," Gwinnett County police spokesman Ed Ritter said Wednesday night. "And our SWAT team made the decision to go in there and neutralize the situation."
All four Gwinnett County firefighters who were being held hostage suffered "superficial" injuries after authorities used explosives "to distract the suspect to get in the house and take care of business," Ritter explained. Their injuries were the result of the explosions, not gunfire, and all four were expected to go home by night's end.
One law enforcement officer was shot in the incident, but his injury is not considered life-threatening, according to Ritter. All those involved in the incident -- including the Gwinnett County police officer -- were in good condition as they were treated at Gwinnett Medical Center, hospital spokeswoman Beth Okun said. Several have been released, she said.
"They are simply relieved that the situation is over," said Gwinnett County Fire Department spokesman Thomas Rutledge. "The firefighters are glad to be getting treated ... and really work on getting their lives back to normal."
The hostage situation began around 3:40 p.m. Wednesday when the firefighters went to a residence in Suwanee "for some type of medical call," Ritter said. Four hours later, he noted authorities still weren't sure whether that call was for a "fake heart attack" or the gunman was actually suffering from a medical condition.
One fire engine and an ambulance were sent to the scene, as is customary, Rutledge said. He explained that the firefighters involved are cross-trained as paramedics so they can provide aid to county residents in purported medical emergencies like this, which happen "hundreds of times throughout the year."
"This is what they do, it's what they do very well," said Rutledge, saying the firefighters had no reason to think this situation would turn violent. "This call seemed to be no different ... They were caught off guard."
Five firefighters had gone inside the home -- a two-story structure, one of many in the neighborhood about 30 miles northeast of Atlanta -- with a stretcher, then a single firefighter ran out about 30 minutes later, according to neighbors. Rutledge said one firefighter was let go so he could move the fire truck from in front of the house.
The house was foreclosed upon in November and was being prepared for sale, said Brad German, a spokesman for Freddie Mac. It was not clear what, if anything, that fact had to do with what unfolded Wednesday.
Jake Major, an 18-year-old neighbor who used to mow the alleged hostage taker's lawn, said he seemed "really nice, ... like a normal guy." His yard, though, "was a mess (and) inside it was just as bad," Major said.
Ritter, the police spokesman, said that the unidentified gunman started making demands related to the house after taking the firefighters hostage.
"The power was turned off along with the cable and cell phone and so on, and he wanted all those things turned back on," said Ritter, adding that "apparently he was going through some financial issues."
Hostage negotiators were on site, as were agents from the federal Bureau of Alcohol, Tobacco, Firearms and Explosives, according to Richard Coes, a spokesman for that agency.
As scores of law enforcement officers converged on the site, Major said his only hope was that everything he was hearing about the situation "was wrong."
"I knew that (once) it had escalated to this level, ... it wasn't going to end well," said Major, who lives about a block away. "Whatever happened, it wasn't going to end well."
Explosions rang out around 7:30 p.m., and soon after ambulances rushed away from the scene.
"Thirty seconds later, I knew everything was OK," said Wesley Gossan, who lived two doors down, of the sequence of big and small explosions, followed by a flurry of gunfire. "Because the (firefighters) walked out, they took their hard hats off."
Ritter explained later that there had been an exchange of "gunfire between officers and that individual."
"This was his call, his decision, this was the result of his actions," the police spokesman said.
"We didn't want it this way. But he was calling the shots."
CNN's David Mattingly reported from Suwanee, and Greg Botelho wrote this story from Atlanta. CNN's Dave Alsup, Chandler Friedman, Vivian Kuo and Carol Cratty contributed to this report.