Mount Vernon police are investigating the murder of a 38-year-old man after an argument at the man's apartment in the early morning hours of Tuesday.

Neighbors told officials that several individuals came to the man's apartment in the 2300 block of Kulshan View Drive where an argument occurred, Mount Vernon Police Department said in a news release. They heard gunshots and the man was hit.

The suspects left the scene and a sheriff's K9 came to search but didn't find anybody, the police department said.

Around noon on Tuesday, detectives got information that led them to a house in the 4300 block of 88th Street NE in Marysville. A 21-year-old man was arrested and police served a search warrant to collect additional evidence.

Later Tuesday around 6 p.m., investigators arrested an 18-year-old Mount Vernon man in the 1500 block of North 18th Street. They served another search warrant to more evidence.

Deputies booked the two suspects into Skagit County Jail. They're both under investigation for second-degree murder and first-degree robbery.

Police took about 12 hours to investigate the crime scene on Kushan View Drive.

Investigators are looking for additional information. Contact them at 360-428-3211 any time of the day or call anonymous tips to 360-336-0632.