Firefighters from around the D.C. region lined up in April to pay their respects to firefighter John Ulmschneider. (Lynh Bui/The Washington Post/Lynh Bui/The Washington Post)

A grand jury on Thursday indicted a man who fatally shot a Maryland firefighter on illegal handgun charges but declined to hand up a murder charge in the death, which occurred as firefighters responded to a 911 call.

The five-minute incident in April occurred when responders to a medical call arrived at the Temple Hills home of Darrell Lumpkin, 61.

Prosecutors on Thursday said Lumpkin has a 1980 conviction for assault in the District, a crime of violence that should have prevented him from owning the handgun he used in the shooting of firefighter John Ulmschneider, 37.

Lumpkin had been sleeping when firefighters, fearing a medical emergency, broke into his home, Prince George’s County State’s Attorney Angela Alsobrooks said. When Lumpkin awoke, Alsobrooks said, he thought the firefighters were intruders. He told authorities he shot in self-defense.

“This is a tragedy that none of us expected, and to be quite candid, one we hope we will never see again,” Alsobrooks said.

The indictment comes three months after the April 15 shooting of Ulmschneider and the wounding of fellow firefighter Kevin Swain and the brother of the shooter. The brother met firefighters at the house after calling 911 because he was worried about Lumpkin’s health.

Lumpkin’s brother asked authorities to check on the welfare of Lumpkin, who is diabetic and might have experienced a blackout or a seizure, authorities have said.

After firefighters knocked several times and announced themselves three times, they made a forced entry, county authorities said. The three men were shot.

Alsobrooks said Lumpkin awoke and thought that there was a criminal break-in.

When deciding whether to indict Lumpkin on a murder charge, the grand jury had to consider his state of mind at the time of the shooting — specifically his intent when he fired the gun and whether he was reasonable in his belief that he fired in justified self-defense.

Self-defense shootings in Maryland use a “reasonable person” standard to determine whether someone should be charged with manslaughter or murder. To avoid charges, legal experts say, the shooter must reasonably believe he was under imminent threat of death or severe bodily harm and that the force used was necessary and reasonable.

After the shooting, Lumpkin gave a lengthy statement to police.

Authorities recovered the weapon used in the shootings and two other handguns from his home, Alsobrooks said.

“He was disqualified from owning those firearms because he had been previously convicted of a crime of violence,” Alsobrooks said.

Lumpkin was charged with three counts of firearm possession with a disqualifying conviction and three counts of firearm possession with a crime of violence conviction.

Lumpkin faces up to 45 years in prison on the six counts of weapons charges, Alsobrooks said.

Lumpkin could not be immediately reached for comment and online court records did not indicate who his attorney was in the case.

A court date has not been set.

Since April, leaders in the Prince George's County fire department have said that firefighters who answered the call for the medical emergency did exactly what they were trained to do the night of the shooting.

“We still stand firm that our personnel did not do anything wrong that evening,” Deputy Chief Benjamin Barksdale said Thursday. “We had extenuating circumstances from a loved one at the scene saying that their brother was inside and needed medical assistance. And that is when we went in there to render aid, unfortunately to a tragic outcome.”

The department has been reviewing policies and procedures to improve firefighter safety after Ulmschneider’s death. Barksdale said the department will move forward with a full internal review of the incident once the criminal investigation into the case is complete.

Morningside firefighter Swain, then 19, who was also shot that night, is still recovering but doing well, Barksdale said.