The head of Minneapolis police has resigned at the city mayor's request after the police shooting of an Australian bride-to-be who had dialled 911.

Minneapolis Mayor Betsy Hodges said she asked Janee Harteau to stand down because she had lost confidence in her in the wake of Justine Damond's killing.

Ms Damond, 40, was shot dead shortly after reporting what she believed was an active sexual assault in the US city on Saturday.

Mayor Hodges was later forced to abandon a press conference she held to confirm Ms Harteau's departure as protesters called on her to quit as well.

A man interrupted her filmed statement, telling her: "We do not want you as the mayor of Minneapolis. You have been ineffective."

Police chief Ms Harteau - who admitted the teacher "did not have to die"and said the death "should not have happened" - confirmed her departure in a Facebook post on the police department's page.

"I've decided I am willing to step aside to let a fresh set of leadership eyes see what more can be done for the MPD to be the very best it can be," she wrote.

It came after Ms Hodges called for "new leadership" in the department.

"I've lost confidence in the chief's ability to lead us further," she said. "It is clear that she has lost the confidence of the people of Minneapolis as well."

Ms Harteau had apologised for the death of Ms Damond in a news conference on Friday.

She said the force had failed to "protect with courage" and "serve with compassion" and said: "These were the actions and judgement of one individual."

Chief Harteau said officer Mohamed Noor and his police partner should have activated their body cameras before encountering Ms Damond.

Neither body cameras nor a squad camera are believed to have captured the incident.

Mohamed Noor was involved in the fatal shooting of Justine Damond. Credit: AP