WALNUT CREEK -- A 22-year-old Walnut Creek man charged at police with a giant chef's knife he had used to threaten his roommate before officers shot and killed him last month, police said Monday.

Anthony Banta Jr., a popular hair stylist, was shot and killed by Walnut Creek police in the early-morning hours of Dec. 27 after officers responding to a 911 call found him at the Diablo Pointe Apartments at 1450 Creekside Drive. He was armed, agitated and refused to put the knife down, said Walnut Creek police Chief Joel Bryden.

On the line with the 911 caller, a dispatcher heard a struggle and a woman screaming before the call ended abruptly, Bryden said.

Four officers arrived at the apartment and entered after their knocks were unanswered, Bryden said. Inside, police allegedly found Banta at the top of the stairs, clutching a chef's knife with a 10-inch blade.

When officers told him to drop his weapon, Banta suddenly charged down the stairs at officers, prompting them to shoot him, Bryden said.

Officers administered aid to the man before pronouncing him dead at the scene.

Upstairs, police found the roommate and an unidentified woman, both locked inside a bedroom, Bryden said. The pair told police that Banta had attempted to break down the door and they believed he was trying to hurt or kill them.

Police declined to say what prompted the dispute between Banta and the other two.

Banta had no criminal record and was a well-liked hairstylist at Salonamour Hair Salon in Walnut Creek, where he was said to have demonstrated "exceptional" talent and had begun fostering a "promising" career.

Banta's family declined to speak about their son or the shooting, but described in an obituary his "smile, gentleness and kindness," and how he "looked past the surface of life and discovered the good in each situation."

The four officers were placed on paid administrative leave but had all returned to full duty as of Monday, Bryden said. He declined to speculate about the officers' decision to use lethal force.

"No officer wants to shoot to kill," Bryden said. "Officers don't shoot and kill anyone unless they are absolutely forced to."

The shooting is being jointly investigated by the Walnut Creek police, the Contra Costa County District Attorney's Office and the Contra Costa County Forensics & Crime Lab, Bryden said. The investigation will take up to four months. This was the first officer-involved shooting in Walnut Creek since 2001 when officers shot and killed 23-year-old Jason Amen Watts inside an electronics store after he reportedly pulled out a gun.

Contact Erin Ivie at eivie@bayareanewsgroup.com. Follow her at Twitter.com/erin_ivie.