A suicide bomber has rammed his explosive-laden car into one of two buses carrying off-duty soldiers in Egypt's turbulent region of northern Sinai, killing 11 and wounding 37.
Security and military officials say the suicide bomber struck when the two buses travelled on the road between the border town of Rafah and the coastal city of el-Arish. The buses were on their way to Cairo, the officials said.
The soldiers belong to the 2nd Field Army, which is doing most of the fighting against Islamic militants waging an insurgency against security forces in Sinai.
The officials spoke on condition of anonymity as they weren't authorised to release the information.
Colonel Mohammed Ahmed Ali, a military spokesman, said the wounded were being treated in military hospitals.
"The precious blood of our sons strengthens our resolve to cleanse Egypt and shield its sons from violence and treacherous terrorism," Ali wrote on his Facebook page.
The northern Sinai region, which borders Gaza and Israel, has been restless for years, but attacks have grown more frequent and deadlier since the July ouster of Islamist President Mohammed Morsi.
There was no immediate claim of responsibility for Wednesday's attack, but suicide car bombings are a signature method by militant groups linked to or inspired by al-Qaeda.
It was the latest in a series of similar attacks targeting army and police facilities and checkpoints.
Earlier this week, a senior security officer who monitors Islamist groups, including Morsi's Muslim Brotherhood, was shot dead as he drove in Cairo's eastern Nasr City district, a Brotherhood stronghold and home to several military barracks.
In a video clip posted on Tuesday on the internet, a militant group, Ansar Jerusalem, claimed responsibility for this week's slaying of the security officer, police Lieutenant Colonel Mohammed Mabrouk said.
Mabrouk said the killing was in retaliation for the recent arrest of female Morsi supporters.
The group had previously claimed responsibility for the attempt on the interior minister's life and an attack on military intelligence compounds in the Suez Canal city of Ismailia and the southern Sinai city of Tor.
Meanwhile, clashes late on Tuesday between revolutionary youths opposed to military rule and police killed a teenager and wounded 41, said Ahmed el-Ansari, head of Egypt's emergency services.
He said the teenager suffered a head wound from a birdshot pellet and died while being taken to hospital.
The violence in Cairo's famed Tahrir Square followed day-long protests marking the second anniversary of clashes between protesters and police on an adjacent street.
Authorities have since Morsi's ouster waged a major crackdown against the Brotherhood, arresting some 2000 top and middle-level members and several thousand followers.
Morsi, along with the group's top leaders, are in detention and face trials on charges that vary from murder and inciting murder to conspiring with foreign powers and corruption.
Supporters of the former president have staged near-daily protests against the July 3 coup, mostly in universities.
The number of protesters, however, has been dwindling, although they occasionally mass several thousand.
