LOWELL — It was just before closing time Wednesday night and Kimseng Seng was alone in his Lowell convenience store, scraping a scratch ticket a customer left behind.
The quiet moment, however, quickly turned violent when two men wearing long pants and hooded sweatshirts entered the store around 8:50 p.m., jumped over the counter, and attacked the 54-year-old Seng, according to surveillance video of the incident.
But Seng, a native of Cambodia who has run The 99 Store on Liberty Street for 17 years, did not go quietly as the two robbers fled the business and ran into the road in opposite directions.
“I tried to chase them across the street. I shoot twice,” Seng said Thursday morning. “I’m working so hard for my family. You can’t do it the easy way. Just come and take my money that I work for. It’s not right. I have to protect myself.’’
Seng said he fired at one of the robbers with the .380 -caliber semiautomatic pistol he keeps in his pocket, but police said he did not hit the suspects. Seng is legally licensed to carry the firearm, police said.
The store owner said it was the first time he fired his weapon at a person. Seng said he panicked.
“The guys, you know, just come in, grab my money. I’m working so hard for that,” said Seng, who lives above his store with his wife and three sons. “It’s not right . . . I have to do something.”
During the robbery, Seng said the suspects demanded money, ordered him not to call the police, and tossed a phone out of his reach. One suspect held Seng down and covered his mouth with a construction glove while the other emptied cash drawers for money transfers and the Massachusetts State Lottery, he said.
Seng told investigators the robbers made off with nearly $10,000, said Lowell Police Captain Timothy J. Crowley. The store owner did not see the suspects brandish a weapon, but another witness told officers he believed one of the men had a gun, Crowley said.
He said police learned of the robbery and shooting from an officer who was patrolling Liberty Street and saw two men running out of the store wearing hoods. As the officer turned his cruiser around, he heard gunfire and then encountered Seng outside the business, Crowley said.
Crowley and a spokeswoman for Middlesex District Attorney Marian T. Ryan said investigators are looking into whether Seng committed a crime by firing the pistol. Police determined one of the two rounds struck a residential building across the street from the store, Crowley said.
He said Seng has been “forthright” about what happened.
“We’re just trying to determine if the facts that he gave us justify the actions that he took,” Crowley said. “You have to look at the totality of the circumstances.”
Police arrested a man near the store about an hour after the robbery, but investigators believe he may be a little taller and younger than the robbery suspects, Crowley said.
Officers asked to speak with the man while they were investigating the robbery, according to Middlesex Assistant District Attorney Tokufumi Noda.
That man, later identified as Matthew A. Fisher, 28, of Lowell, ran from police and into traffic, where he was almost struck by an car, Noda said. He also ditched a backpack in which police found a loaded TEC-9, Noda said.
Fisher was arraigned Thursday afternoon in Lowell District Court on firearms and other charges.
“It’s still under investigation, but at this time it doesn’t look like he’s one of the suspects at the convenience store,” Crowley said.
Seng was back at work Thursday morning, when one customer praised him for doing a “good job.”
His son, Robert, 21, said he’s glad nothing else happened.
“He has [the pistol] so he has to use it if he feels threatened,” he said.
Some in the neighborhood, however, worried that Seng’s actions could have endangered others.
Lawrence Mumbauer, 63, lives in the apartment building that was struck by a round from Seng’s pistol. The bullet ricocheted off an exterior bannister and struck siding at the front of the residence.
His neighbor, Wendy Ray, 46, said 10 children live in a multifamily home across from the store and she often sits outside to smoke.
“I could have been sitting here,” she said. “It was scary.”
Mumbauer said the bullet came close to entering his apartment.
“The bullet could have went anywhere,” he said. “By doing what he did, you don’t know who you’re going to hit.”John R. Ellement of the Globe staff contributed to this report. Laura Crimaldi can be reached at firstname.lastname@example.org. Follow her on Twitter @lauracrimaldi.