Police in London, U.K. say they have arrested a fifth suspect after two women said they were beaten by a group of males on a city bus for refusing to kiss in front of them.

In a statement on Saturday, Metropolitan Police said they arrested a 16-year-old boy earlier that morning on suspicion of robbery and aggravated grievous bodily harm. Four other teenagers between the ages of 15 and 18 were arrested the day before in connection with the same attack. Those males remain in custody at a separate police station in London, according to the statement.

Earlier this week, Melania Geymonat described the incident in a detailed Facebook post. She said she and her girlfriend Chris boarded the upper level of a double-decker bus in the early hours of May 30 in London’s West Hampstead neighbourhood.

Geymonat said she and her partner must have “kissed or something” when they were on the bus because they were approached by a group of males who started “harassing” them.

“They started behaving like hooligans, demanding that we kissed so they could enjoy watching, calling us ‘lesbians’ and describing sexual positions,” she wrote.

The confrontation quickly turned physical and Geymonat said she and her partner were punched multiple times by the group of males.

Police said the women, who are both in their 20s, were attacked and punched several times. They also said a phone and a bag were stolen during the assault.

“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,” Geymonat said.

Geymonat also posted a photo in the aftermath of the attack that showed her and Chris sitting on the bus with blood smattered across their faces and clothing.

Investigators said the women were taken to hospital to be treated for facial injuries. Geymonat said she wasn’t sure yet if her nose had been broken during the assault.

“This was a disgusting attack on two women who appear to have been picked out and targeted by a group of youths,” Det. Supt. Andy Cox said in the statement. “When the women tried to reason with the group, the attack escalated to an assault.”

Cox said detectives are currently in the process of reviewing CCTV footage from the attack. He also repeated investigators’ earlier appeal for witnesses who were on the bus before or after the attack to come forward and speak to police.

“A number of active enquires are in hand to trace other individuals suspected to have been involved in the incident,” he said. “Our efforts to trace all the suspects involved and bring them in for questioning will be relentless.”

Police also said that attacks of this nature are rare on London buses.

“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,” Cox said.

The case has received global attention and widespread condemnation, including from British Prime Minister Theresa May, Opposition Leader Jeremy Corbyn, and London Mayor Sadiq Khan who called the attack “disgusting” and “misogynistic.”

None of the allegations has been tested in court.