The crimes took place during the past few days.
The pregnant woman was kidnapped and gang-raped while on her way home from work at a nightclub early on Monday.
The woman’s male colleague told The Star they finished work at 4am and were attacked on Lilian Ngoyi (formerly Bree) Street.
Their names have been withheld to protect the woman's identity.
“We were walking on Bree Street when one guy grabbed her,” the co-worker said. “I told him to stop what he was doing and we ended up in a fight."
"From there, all I saw were a bunch of armed men surrounding me. They started hitting me, until I ran to get help from a woman who sells newspapers around the corner,” said the 23-year-old bartender.
Some of the assailants proceeded to assault him, while the others stripped his female colleague.
The woman was then dragged into a dilapidated block of flats nicknamed Mnyama Ndawo, meaning "dark place", he said.
“When the police arrived, we heard screaming from the building, which has no electricity. When we found her, there were men standing in a queue waiting to have sex with her,” said the traumatised man.
Police spokesperson Captain Xoli Mbele said 11 suspects were arrested and were expected to appear in the Johannesburg Magistrate’s Court on charges of kidnapping and rape. The woman is in Charlotte Maxeke Johannesburg Hospital, where she is receiving counselling.
Meanwhile, a devastated mother is mourning the death of her 27-year-old daughter, whose body was discovered on Sunday in Naledi, Soweto.
Lerato Tambai Moloi was last seen in the early hours of Sunday at the Gift’s Inn tavern with a 38-year-old man. He was arrested and was to appear in the Protea Magistrate’s Court on Wednesday.
Lerato's uncle, Bongani Moloi, said the family were particularly traumatised by the manner in which they found out about her death.
“We saw pictures of her circulating on social media. No parent would like to find out their child died in that manner,” he said.
He appealed to the public to refrain from sharing the gruesome images of his niece’s body.
The young woman was stoned to death after being sexually assaulted.
In a separate but equally horrific double murder, police are searching for suspects in connection with the murders and suspected rape of two women, Popi Gumede, 24, and 28-year-old Bongeka Phungula.
Gumede’s body was found on Friday in Naledi and Phungula's the next day in Tladi.
“The pair are from KwaZulu-Natal and were living together in Zola. Their bodies were identified by their families,” police spokesperson Captain Mavela Masondo said.
The news of Moloi’s murder comes as the Love Not Hate project launches a new campaign demanding justice for LGBTI victims of hate crimes on the eve of the International Day against Homophobia and Transphobia (IDAHOT), which takes place on Wednesday.
The “5 – Justice Denied” campaign aims to highlight the appalling delays and injustices in five ongoing LGBTI hate-crime cases.
The five cases include shocking incidents of the rape, torture and murder of LGBTI people, as well as anti-LGBTI hate speech.
“Not only is the criminal justice system failing these and other LGBTI victims of hate, but so too are the structures initiated by the government to tackle these crimes,” said Lerato Phalakatshela, the hate crimes manager at the OUT LGBT campaign.
Marike Keller, policy development and advocacy co-ordinator at Sonke Gender Justice, said: “We are facing an epidemic of gender-based violence (GBV) in our country.
"These cases of GBV are unfortunately nothing new – it is only with targeted media attention that it seems to be a trend Urgent action is needed from the government.”
Women and Men Against Child Abuse spokesperson Vincentia Dlamini attributed the prevalence of this type of crime to a lack of decent role models for men in society.