(CNN) -- Two British female activists were raped two days ago in the eastern city of Benghazi and four suspects have been arrested, Libyan officials said Thursday.
In a statement posted on his official Facebook page, Libya's Deputy Prime Minister Awad al-Barassi said the women, who are sisters, were kidnapped Tuesday and raped in front of their father.
According to al-Barassi, the young women are British citizens who were born in Pakistan and were part of Turkish non-governmental organization IHH's aid convoy to the Gaza Strip.
Al-Barassi and Libya's Interior Ministry said four men involved in the incident had been arrested and security forces in Benghazi were pursuing a fifth person.
While al-Barassi said it was unclear whether the men were part of the "revolutionary brigades" that serve under the country's security ministries, the Interior Ministry blamed the incident on "outlaws."
The Libyan state news agency LANA, quoting security sources in Benghazi, reported that other members of the aid group also were assaulted by a different armed group and two activists who were kidnapped are still missing.
Al-Barassi said he visited the victims and met with their father at a Benghazi hospital on Thursday to apologize on behalf of the Libyan people and government for this incident. He told them it didn't represent the Libyan society and its Islamic values.
He said the family was in a "very bad psychological state."
In an interview with a Libyan TV channel, al-Barassi said the women and their father were on their way to Benghazi's Benina International Airport when they were stopped at a checkpoint nearby. The women and their father were kidnapped, and the man witnessed the rape of his daughters, he said.
The deputy prime minister said he was in touch with the British ambassador to Libya throughout the day.
"We are aware of an incident in Libya, involving a number of British nationals who were part of an aid convoy. We are providing consular assistance," a U.K. Foreign Office spokesperson told CNN.
The Interior Ministry said in a written statement that the father, along with a translator, notified police of the incident on Wednesday.
Lt. Majdi al-Erfi, a spokesman for the Interior Ministry, said the family had returned to Benghazi after the aid convoy was turned back by Egyptian authorities. He said the family was on a bus when they were stopped at an "unofficial checkpoint" by armed young men in military uniforms.
According to al-Erfi, the family was held at the checkpoint and "its members assaulted while two outlaws ... kidnapped two of the young women and took them to a farm on the outskirts of the city to carry out the crime."
The remaining members of the humanitarian aid convoy are at the Turkish consulate in Benghazi, officials said.
Al-Barassi promised the results of the investigation would be made public and said those involved would stand trial soon.
He said the young women were wearing veils and "Free Palestine" T-shirts.
Two years after the start of the revolution and a bloody civil war that overthrew Libyan dictator Moammar Qadhafi in 2011, the government is still struggling to exert its authority and control the hundreds of militias, most of which continue to operate freely across the country.
CNN's Susannah Palk contributed to this report.