Two Afghan immigrants have been arrested in Sweden in connection with a three-hour gang rape of a woman that was live-streamed on Facebook.

The two men, aged 18 and 20, were arrested in Uppsala after social media users alerted authorities of the brutal attack, The Local reported.

A third man, a 24-year-old Swedish citizen, was held for allegedly failing to reveal the rape, according to court documents obtained by The Local.

The suspects–who cannot be identified under Swedish law—have not been charged but deny the accusations.

“I have seen stronger evidence in my days,” the 24-year-old’s lawyer, Andreas Welin, told Swedish news agency TT after a pretrial hearing.

Christer Söderberg, who is representing the 20-year-old, said: “A woman is said to have been raped in an apartment. He is suspected of that. He denies any criminal offense. He has given, in my opinion, a perfectly coherent story about what happened.”

An online witness said armed thugs pulled the woman’s clothes off and sexually assaulted her before cops arrived and turned off the camera as she lay unconscious.

Uppsala’s deputy chief prosecutor, Magnus Berggren, told The Local that police obtained still images and footage, but were still seeking the video sequence allegedly showing the rape.

“In order to get as clear a picture as possible we are questioning people who have at least seen parts of the live streaming on Facebook,” Berggren said.

“A film would, of course, have been central evidence, but there is also other evidence,” he added.

Lead prosecutor Pontus Melander said authorities have asked Facebook for help to retrieve the video.

“Facebook has said that they want to cooperate, but they are based in the US so we need international legal aid, which I have requested,” he said.

Josefine Lundgren, 21, called authorities immediately when she saw the livestream, The Sun of the UK reported.

“He pulled her clothes off and lay on top of her,” she told Sweden’s Expressen about one of the men.

A few hours later, she saw a uniformed officer interrupt the sick broadcast as he arrived at the scene. He demanded that the men accompany him to the police station.

“I first thought it was a poorly orchestrated joke,” another online witness told Expressen.

“The first thing you think is, ‘How can you do such a thing to a girl? And how can you do it live when you know that you are going to go there?'” the former member of the closed Facebook group said. “I think of course it is screwed—totally sick.”

In Sweden, suspects in serious crimes can be held without charges with a court’s approval if there is a risk they will flee the country, obstruct an investigation or continue to commit crimes.