BROOKHAVEN, Ga. — A stray bullet struck and killed an English astrophysicist while he was inside an Atlanta-area apartment, authorities say.

Matthew Willson, 31, of Chertsey, Surrey, England, was visiting his girlfriend in the United States when he was hit by a bullet that pierced the wall of the apartment. The shooting happened early Sunday morning, only three days into his visit.

“He was supposed to be here for three months because we’ve been long distance for a while,” Katherine Shepard, his girlfriend of three years, told WSB-TV. “I picked him up from the airport, took him to his favorite eating location, and the next day, he’s gone.”

Shepard, whose apartment is in the Atlanta suburb of Brookhaven, who told the television station that the couple woke up on Jan. 16 to the sound of more than 30 gunshots coming from an apartment complex directly behind Shepard’s. A bullet traveled through Shepard’s wall, hitting Willson, she said.

“I held him for another 20 minutes while we waited for the ambulance,” she said. “And while we were waiting, there were more gunshots fired.”

Police were in the vicinity pursuing reports of gunfire when the 911 call from Shepard came in. Sgt. Jake Kissel of the Brookhaven criminal investigations division said that once officers arrived at the scene, they rendered aid until paramedics arrived.

“Dr. Willson was transported to a local trauma center where he succumbed to his injuries,” Kissel said in a statement. The shooting appeared to be a “random act involving individuals participating in the reckless discharge” of firearms.

Willson was being mourned by family, friends and his alma mater, the University of Exeter.

“Matthew Willson was a former PhD student at the University of Exeter and much-loved member of our astrophysics team,” a university spokesman said in a statement.

No arrests have been announced. Brookhaven police have asked for witnesses or anyone with information about the shooting to contact them or submit an anonymous tip to Crime Stoppers at 404-577-TIPS (8477).