A 45-year-old man who was killed Monday morning after an argument with a group of men who entered his Gaithersburg apartment died of a stab wound, Montgomery County police said Tuesday, citing a report by Maryland’s Office of the Chief Medical Examiner.

Police said the investigation into Cesar Smith’s killing continues, and they have no one in custody. Police initially said the man had been shot. Smith may have had some association with the suspects, police said, and investigators are looking into whether robbery was involved.

It remains unclear whether anything was stolen, according to Officer Rebecca Innocenti. “We don’t think it was a random event,” she said.