The Alberta Serious Incident Response Team is investigating after a man arrested early Tuesday for public intoxication died in Edmonton police custody.

The man is believed to be around 40 years old but hasn't been positively identified, the Edmonton Police Service said in a news release.

Police had responded to a call at a gas station in the Lansdowne neighbourhood near 51st Avenue and 122nd Street at 4 a.m.

Officers were told the man, who appeared to be on drugs, had entered the gas station "and was behaving in an agitated manner," police said.

The man was arrested for being intoxicated in public and taken to the Southwest Division station in Windermere.

Around 7 a.m., he was found unresponsive in his holding cell. He was pronounced dead on scene by Emergency Medical Services.

An EPS spokesperson said details could not be provided on how often the man was checked while he was in the holding cell, but said protocol calls for security checks to be conducted every 15 minutes and arousal checks every hour.

The director of law enforcement was notified of the death and directed ASIRT to investigate.

ASIRT is a provincially-appointed body that investigates incidents where policy may have caused the serious injury or death of a civilian, and serious allegations of police misconduct.

EPS said it won't provide further comment.