Two Irish women were arrested Saturday after being trapped with hundreds of people in a Cairo mosque surrounded by Egyptian security forces, one of them told Irish state broadcaster RTE.
The pair are children of the imam of Ireland's biggest mosque in Dublin and were on holiday in the Egyptian capital with a sister and a teenage brother who were also in the mosque.
The family took refuge in the Al-Fath mosque after dozens of people were killed in violent clashes between supporters of ousted Islamist president Mohamed Morsi and the security forces in Cairo on Friday.
Omaima Halawa, 21, and her sister Fatima, 23, were taken into custody by the Egyptian security forces when they left the mosque.
Although their mobile phones were taken from them, they managed to borrow one and called relatives in Dublin saying they had been arrested, RTE reported.
The whereabouts of their sister Somaia, 27, and brother Ibrihim, 17, are unknown.
Omaima earlier said that security forces had thrown tear gas at them inside the building.
"We are surrounded in the mosque both inside and outside," she told RTE. "The security forces broke in and threw tear gas at us."
The four had gone to Egypt with their mother for a holiday while their father, Hussein Halawa, remained in Ireland.
Another of the family's children, Nasaybi, said from their home in Dublin that her siblings were enduring a horrifying experience and she felt helpless.
She said: "We are really worried. We do not know how to help them. We are just trying to support them by calling and giving them some hope that they will get home safely."
A spokesman for Ireland's foreign ministry said embassy staff had contacted the four and were working with the Egyptian authorities to try to secure their safety.
Egyptian police cleared Islamist protesters from the mosque on Saturday after a standoff that included exchanges of fire, as the death toll from four days of violence surpassed 750.
The clashes came as the government said 173 people had been killed in the past 24 hours alone, bring the country's death toll to more than 750 since Wednesday, when police cleared two camps of Morsi loyalists in the capital.
The bloodshed followed the deaths of 578 people in a crackdown on Wednesday, splintering the army-installed interim government and drawing international condemnation.