A 45-year-old man who was found dead in a Gaithersburg apartment early Monday morning was stabbed to death, police said.

The medical examiner's office ruled Tuesday that Cesar Smith, of Gaithersburg, died because a single, fatal stab wound.

Montgomery County police said that Smith was in an apartment on Whetstone Drive with at least one other man when multiple people entered. The group members separated the two men, and the group was heard arguing with Smith before they left the apartment. The other man who had been in the apartment then found an injured Smith and called police.

Investigators believe that the incident was not random.