A female couple were battered by a gang of four men after they refused to kiss "for their entertainment" on a London night bus.
Four arrests have been made in relation to the attack, the Met Police said in a statement.
The males, aged between 15-18, were taken into custody on suspicion of robbery and aggravated GBH.
Melania Geymonat, 28, and her girlfriend Chris had been on a date in the capital last Wednesday and were heading home on the top deck of the bus when the men started abusing them.
When they refused to kiss at the demand of the gang, they were viciously attacked. They were also later robbed of a phone and a handbag.
Prime Minister Theresa May has condemned the assault. She said: "This was a sickening attack and my thoughts are with the couple affected.
"Nobody should ever have to hide who they are or who they love and we must work together to eradicate unacceptable violence towards the LGBT community."
In a post on Facebook, Ms Geymonat - who worked recently as a Ryanair air hostess and is originally from Uruguay - said: "I’m tired of being taken as a sexual object, of finding out that these situations are usual, of gay friends who were beaten up just because.
"We have to endure verbal harassment and chauvinist, misogynistic and homophobic violence because when you stand up for yourself s--- like this happens.
"By the way, I am thankful to all the women and men in my life that understand that having balls means something completely different.
" I just hope that in June, Pride Month, stuff like this can be spoken out loudly so they stop happening."
Describing how the attack unfolded, she wrote: "Last Wednesday, I had a date with Chris. We got on the night bus, heading for her place in Camden Town, climbed upstairs and took the front seats.
"We must have kissed or something because these guys came after us. I don’t remember if they were already there or if they got on after us. There were at least four of them.
"They started behaving like hooligans, demanding that we kissed so they could enjoy watching, calling us 'lesbians' and describing sexual positions. I don’t remember the whole episode, but the word 'scissors' stuck in my mind.
"It was only them and us there. In an attempt to calm things down, I started making jokes. I thought this might make" them go away.
"Chris even pretended she was sick, but they kept on harassing us, throwing us coins and becoming more enthusiastic about it.
"The next thing I know is that Chris is in the middle of the bus fighting with them. On an impulse, I went over there only to find her face bleeding and three of them beating her up.
"The next thing I know is I'm being punched. I got dizzy at the sight of my blood and fell back. I don’t remember whether or not I lost consciousness.
"Suddenly the bus had stopped, the police were there and I was bleeding all over. Our stuff was stolen as well.
"I don’t know yet if my nose is broken, and I haven’t been able to go back to work, but what upsets me the most is that violence has become a common thing, that sometimes it’s necessary to see a woman bleeding after having been punched to feel some kind of impact."
She is still waiting to find out if her nose is broken, and is off work due to the attack.
London Mayor Mr Khan is among those to have expressed his anger at the attack, and he tweeted: "This was a disgusting, misogynistic attack. Hate crimes against LGBT+ people will not be tolerated in London. The Metropolitan Police are investigating. If you have any information about this call 101 to report it."
Horrified to see this homophobic attack against two women simply trying to enjoy a night out in West Hampstead. There can be no excuses, no space, for such obscene behaviour. My full solidarity is with these women and the UK's LGBT community.https://t.co/ViajxDdERd— Tulip Siddiq (@TulipSiddiq) June 7, 2019
The MP for the constituency in which the attack occurred, Tulip Siddiq, tweeted: "Horrified to see this homophobic attack against two women simply trying to enjoy a night out in West Hampstead. There can be no excuses, no space, for such obscene behaviour. My full solidarity is with these women and the UK's LGBT community."
Defence Secretary Penny Mordaunt added: "Appalled to see this kind of homophobic violence in the U.K., there’s no place for this kind of vile behaviour in our society. Please contact
@MetCC if you have any information."
Detective Superintendent Andy Cox said: “This was a disgusting attack on two women who appear to have been picked out and targeted by a group of youths. The suspects have made a number of homophobic comments towards the couple before throwing coins at them. When the women tried to reason with the group, the attack escalated to an assault.
“CCTV footage from the attack is being reviewed by detectives. We continue to appeal for information from the public, particularly those who were present on the bus before or after the attack to come forward and tell police what they saw.
“A number of active enquires are in hand to trace other individuals suspected to have been involved in the incident. Lots of people will understandably be outraged by this attack. Our efforts to trace all the suspects involved and bring them in for questioning will be relentless.
“Attacks of this nature on London buses are rare. I would like to reassure those heading out over the weekend that extra uniformed and plain clothes Safer Transport officers will be out on patrol working to keep them safe and prevent crime.”