More than 100 women and girls have come forward with reports of sexual assault and robbery by gangs of men in the German city of Cologne on New Year's Eve.
Victims have described chaos outside the city's main station, as the men carried out dozens of attacks with little apparent response from the authorities.
Correspondents said the identification of the attackers as North African or Arab in appearance has caused alarm in Germany because of the influx of more than a million migrants and refugees in the past year.
Some of the women caught in the violence have begun speaking of their ordeal.
'They grabbed our arms'
Michelle told the BBC News how she and her friends became surrounded by between 20 and 30 men, who were speaking a foreign language.
"They grabbed our arms... pushed our clothes away, and tried to get between our legs or I don't know where.
"They got everything we had in our pockets."
She said German police needed to provide more protection for women and girls.
"We are all really shocked that something like this could happen, especially at an event like New Year's Eve."
'They could rape us and nobody would notice'
One woman, whose identity has been protected, told German television how gangs of men assaulted her in the crowd.
"All of a sudden these men around us began groping us," she said. "They touched our behinds and grabbed between our legs. They touched us everywhere.
"So my girlfriend wanted to get out of the crowd. When I turned around one guy grabbed my bag and ripped it off my body."
She said she felt in extreme danger, but there were no police officers to help.
"I thought to myself that if we stay here in this crowd they could kill us, they could rape us and nobody would notice. I thought we simply had to accept it.
"There was no one around us who helped or was in a position to help. All I wanted was to get out.
"I was scared that I wouldn't leave this crowd alive. I was scared that if someone showed up with a knife I could be raped in the middle of the street."
'They felt they were in power'
One victim, named as Busra, spoke of a sense of lawlessness outside the station, where the attackers felt they could do as they pleased.
"They felt like they were in power and that they could do anything with the women who were out in the street partying," she said.
"They touched us everywhere. It was truly terrible."
'The scars will stay'
Jenny said she believed attackers put a firecracker into her hood to deliberately distract her while they stole her phone.
"I heard a sizzling sound in my hood I somehow tried to get it out of the hood," she said. "Then it fell into my jacket and burned everything.
"The scars will stay. I was lucky that it didn't explode.
"My mobile phone was gone afterwards. I think they did it on purpose so they could steal my phone."
'I was touched between my legs'
Muriel described through tears how she was sexually assaulted by a large group of men.
"We were fondled, I was touched between my legs. My friends also were fondled," she said.
"There were quite a big group of people, maybe 30 or 40.
"You didn't know who to trust. You tried the whole time to push everyone else away from you."
'We all were scared'
A British woman visiting Cologne said fireworks had been thrown at her by a group of men who spoke neither German nor English.
"They were trying to hug us, kiss us, make us walk with them. We refused," she told the BBC.
"One man stole my friend's bag. Another tried to get us into his 'private taxi'.
"I was scared. We all were scared.
"I will never go back to Cologne and... I've told my friends and family never to go there until this situation is under control."
'We ran to these police cars but there was no one there'
Many of the victims have described a lack of police officers on the streets, despite threatening crowds gathering outside the station.
"There were so many people there that I no longer was in control of myself where to go or how to defend myself," one woman, Evelin, told German television.
"We wanted help. We ran to these police cars but there was no one there.
"We know very well that the police at that moment were so understaffed that they couldn't deal with this, that we women had to go through something like that."