Four people were killed in clashes between supporters and opponents of ousted Egyptian president Mohamed Morsi as his family said they will take legal action against the army, accusing it of abducting the country's first democratically-elected president.
Two people died in clashes in Qalyub, north of Cairo, and a third was killed when he fell under the wheels of a train as he tried to flee, the security source told AFP.
Morsi has been held at an undisclosed military facility since the army removed him from office on 3 July, suspended the constitution in the wake of huge street protests against his one-year rule.
The army says Islamist Morsi is being detained for his own safety.
"There is no legal or constitutional basis ... for detaining someone not accused of a crime for his own safety," Morsi's son, Osama, said in a news conference, the family's first formal appearance since his father was forced from office.
He said the family would take immediate legal action against Abdel Fattah al-Sisi, the army commander and Defence Minister who played a central role in forcing Morsi from office, both "inside Egypt and at an international level"
Osama said the family had not been able to make contact with their father since he was removed from power and had no information on the state of his health.
"(Morsi's) arrest and that of his advisors is completely illegal," said Heba Morayef, Egypt director of Human Rights Watch. Under international law, she said, the maximum time someone can be held without charge is 48 hours.
Morsi's Muslim Brotherhood accuses the army of orchestrating a military coup. It denounced a move, launched on Sunday, to revise Egypt's constitution, drafted last year by an Islamist-dominated body and adopted despite objections from Christians and liberals. The Brotherhood calls the military-backed interim government illegitimate.