A senior Met Police officer has said he cannot apologise for the force's actions at a vigil for Sarah Everard.
Officers handcuffed women and removed them from the gathering on Clapham Common in London on Saturday evening.
Deputy Commissioner Sir Stephen House told City Hall his officers were "doing their duty as they saw it" to enforce Covid legislation at the event.
He said some officers had been on the receiving end of "abuse and violence" and had plastic bottles thrown at them.
Hundreds gathered at the bandstand in Clapham Common to pay their respects to Ms Everard, who went missing on 3 March while walking home from a friend's house.
Her remains were later found in woodland in Kent and Met Police officer Wayne Couzens, 48, has been charged with the 33-year-old's kidnap and murder.
The Met has been widely criticised by senior politicians after footage showed officers detaining women.
Speaking to the London Assembly's Police & Crime Committee, Sir Stephen said officers had to balance "Covid-19 regulations with the human rights of expressing emotions", but had seen a "distinct change in tone" at about 18:00 GMT.
He continued: "People began to gather around the bandstand and some people began to make speeches.
"Inevitably, when that happened, the crowd compacted and compressed to hear what was being said and it became a much more difficult situation for us to reconcile with Covid legislation.
"We believe that when the crowd density increased, Covid regulations were no longer being followed."
Sir Stephen said the atmosphere became "very hostile" and plastic bottles were thrown at some officers
He added: "We certainly didn't want to see a vigil in the memory of Sarah to end in the scenes we saw on Saturday night.
"We fully understand the strength of feeling that the images provoked and we understand why it has provoked a national debate.
"We have heard now for a year that Covid legislation in its various forms makes the job of policing very difficult and that simply couldn't have been illustrated more clearly by the events of Saturday."
A minute's silence was held before the committee meeting in memory of Ms Everard.
Home Secretary Priti Patel has instructed the police watchdog, Her Majesty's Inspectorate of Constabulary (HMIC), to "conduct a lessons-learned review into the policing of the event".