Police in Philadelphia say a man who had just robbed a Dunkin store in the city's Mayfair neighborhood was shot and killed early Tuesday morning by an armed citizen who arrived at the shop just as the robber and his accomplice were fleeing the scene of the crime. 

According to authorities, the donut shop was the last stop for the pair after allegedly committing several other armed robberies just hours before.

Investigators believe the man and another man had robbed two gas stations earlier in the night, before descending on the Dunkin’ for a third round, according to a law enforcement source with knowledge of the case.

Their night began around 12:30 a.m., when the two men held up a 7-Eleven at 6800 Bustleton Ave., said the source, who spoke on the condition of anonymity. About four hours later, investigators believe those same men robbed another 7-Eleven at 1811 E. Luzerne St.

Later, at about 5 a.m., the men — dressed in similar clothes to the earlier robberies — went to the Dunkin’ at 6401 Roosevelt Boulevard, the source said.

They held up the cashier as well as a bystander, who had stopped for coffee on his way to work, said the source. That man’s brother arrived just as the robbers were fleeing, the source said, and yelled at the men, dressed in ski masks, to stop. He followed as they ran down a back alley, and then, as one of the alleged robbers pulled a gun and shot at him, the bystander shot back, striking the robber once and killing him, the source said.

The robber's accomplice continued running, and as of Thursday afternoon police haven't announced any named suspect or an arrest in the robbery. The armed citizen possessed a valid concealed carry license, according to the Inquirer's source and as of yet has not been charged with any crime. If the gun owner did fire back at the robbers, he clearly would have been justified in using deadly force to protect himself from harm, and from a legal standpoint he should be in the clear. 

Should he have chased after the robbers as they were fleeing the scene of the crime, though? Again, from a legal perspective there's nothing wrong with doing so, but most of us are taught to avoid conflict whenever possible when we're carrying a firearm. Running after the guys who just held up the donut shop may have been pure instinct instead of a thought-out decision, but it also put him at risk of getting shot. 

On the other hand, if the perpetrators really were responsible for at least two other armed robberies on Tuesday, it's almost certain that they've committed others in the past and would have committed more in the future. At least one of them clearly wasn't opposed to using violence in an effort to get away, and while no one besides the assailant was injured in this robbery, there's no guarantee that his future victims would have emerged from their encounter unharmed. 

Who knows how many lives might have been saved because this concealed carry holder decided to pursue the suspects and was able to fire back in self-defense after one of them tried to kill him? I'm not sure that I would have responded the same way if I were in his shoes, but it's hard to criticize someone for trying to stop a pair of armed robbers from getting away with their crime.