A man was shot to death in a Downtown apartment after an argument Sunday night, and police are still searching for the gunman, according to the Long Beach Police Department.

Police said the attack happened while a small group of people was gathered in an apartment on Atlantic Avenue just north of Broadway. When an argument broke out shortly before 9:30 p.m., a man pulled out a gun and shot another man multiple times, the department said in a statement.

The gunman fled, and when police arrived, they gave first aid to the wounded man until paramedics arrived and determined he was dead, the LBPD said.

It’s not clear what sparked the argument.

“The investigation to determine the motive remains underway,” police said. “Detectives are actively investigating the relationship between all parties involved, including the victim, suspect, the other persons gathered at the apartment, and the apartment itself, to determine their role in the incident.”

A detailed description of the shooter wasn’t immediately available. Police said he fled on foot.

The Los Angeles County Medical Examiner-Coroner is still working to identify the victim and notify his next of kin. Police said he’s a man in his 40s. Nobody else was hurt, police said.

Police asked anyone with information to contact detectives Michael Hubbard or Leonel Valdez at 562-570-7244. Anonymous tips may be submitted through Crime Stoppers by calling 800-222-TIPS, downloading the “P3 Tips” app to your smartphone or by visiting lacrimestoppers.org.