As more details emerge about the fatal police shooting that left a 48-year-old man dead in a homeless shelter on Saturday, advocates have raised concerns about how officers approached the deadly encounter.

Posts on social media indicate the man killed, a dockworker, may have been suffering from a mental health crisis over the past week.

And the American Civil Liberties Union of Oregon tonight questioned whether officers needed to shoot a man holding a knife who was separated from officers by the length of a room.

"Bystander video of the fatal shooting of a man in a homeless shelter in Portland last night raises serious questions about how police handled the situation and whether lethal force was called for," says ACLU executive director David Rogers. "Trained police officers should use the least amount of force necessary."

Portland police training may have led officers to open fire on a man armed with a knife from the considerable distance shown in the graphic videos captured by witnesses in the shelter.

A 2016 review of Portland Police Bureau training, published by the OIR group, which regularly analyzes PPB's practices, raised concerns with a long-taught "21-Foot Rule."

The rule, which an officer told a grand jury he had been taught in training, says that officers should not let a suspect with an "edged weapon" like a knife approach closer than 21 feet. A review of the rule in 2009 led several police chiefs to say that the "21-foot rule should never be seen as a green light to use deadly force or as creating a 'kill zone.'"

The OIR Group, a private consultant, urged Portland police to "ensure that its officers have not misinterpreted the principles behind the 21-foot rule and provide more contemporary training designed to ensure that officers recognize the appropriate considerations in determining whether and when to use deadly force against someone wielding an edged weapon."

Police have not yet identified the officers who fired the fatal rounds, or the man they killed. But family members said he was John Andrew Elifritz. His Facebook page says he was a 48-year-old shipyard worker with a young daughter.

Social-media posts from the mother of Elifritz's child, and their close friends, indicate that he was suffering from a mental health crisis over the past week.

Those posts date from before and after police killed Elifritz.

"John hadnt been himself for like the last week," a family friend wrote.

Another friend of Elifritz posted on his Facebook page, saying: "My friend John, was also in crisis when, he was profiled and murdered."

Court records show that Elifritz had been convicted of motor vehicle theft in the 1990s. He was also convicted of reckless driving and endangering another person in 2013.

That's relevant because on Saturday, police were pursuing a man who allegedly stole a car by force, crashed it, and then fled the scene. Officers say they followed Elifritz to the homeless shelter, where he had interrupted an Alcoholics Anonymous meeting. Witnesses say Elifritz had been cutting himself with a knife when police showed up at the shelter.

Bystander videos show people hiding in corners of the room as officers entered and shouted for Elifritz to drop the knife he was holding. Elifritz at one point responded by yelling "No."

Officers appear to fire several bean bags at Elifritz before entering the room and firing bullets at the man as he stood across the room, separated from officers by several feet and at times by a short wall forming a barrier between them.

While Portland police have not yet identified the officers involved in the shooting, the agency did say those involved had already been placed on paid administrative leave pending a full investigation.

PPB spokesman Sgt. Christopher Burley says the agency cannot comment on the bystander videos that captured the moments leading up to the shooting, but the agency is aware of the footage.

Mayor Ted Wheeler urged the public to remain patient as investigators looked into the circumstances of the shooting.

"The loss of a life is always tragic," he said in a statement. "My priority is to discover the facts and circumstances regarding this incident. Already, there are those who want to immediately define what happened. It would be highly irresponsible for me to participate in speculation at this time."