At least six soldiers have been killed and 17 others injured in two near-simultaneous car bomb explosions at military targets in Egypt's violence-plagued Sinai Peninsula.
Two cars driven by suicide attackers drove on Wednesday into the outside gates of the military intelligence service building in the Imam Ali area in Rafah, adjoining the Gaza Strip, the Palestinian territory governed by Hamas.
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One of the cars exploded at the checkpoint outside the building, apparently targeting an armoured personnel carrier. The other one exploded further inside, bringing down a two-storey building being used by local military intelligence.
Witnesses said the powerful blasts shattered the windows of other buildings in the area.
An armed group, Ansar Beit al-Maqdis (Partisans of Jerusalem in English), claimed responsibility for the attack in a message posted on its Facebook page.
The Sinai-based group has also claimed responsibility for an attack last week that targeted the Egyptian interior minister, and promised more attacks in revenge for a crackdown on the country's Islamists.
The bombings appear to be a response to recent military action against rebel hideouts in northern Sinai that reportedly left three dozen people dead.
Troops and armour
The Egyptian military has poured troops and armour into Sinai to crush an uprising that surged after the army overthrew the Muslim Brotherhood's President Mohamed Morsi on July 3.
In its statement, Ansar Beit al-Maqdis blamed Mohammed Ibrahim, the interior minister, and army chief Abdel Fattah el-Sisi for the killings of hundreds of Morsi's supporters.
"We call on all Muslims in Egypt to stay away from all military and interior ministry installations to preserve their lives," the group said.
Shortly after Wednesday's attack, the Egyptian authorities closed the Rafah crossing until further notice due to the security situation in the Sinai.
Al Jazeera's correspondent in Cairo, who cannot be named for security reasons, said the region was impoverished, making it more vulnerable to fighting.
"A lot of people in the Sinai thought that life would get better after the revolution, but that hasn't happened. It is a pretty fertile recruiting ground," the correspondent said.
"It is difficult to independently verify information about these attacks. This is a very tightly controlled military zone."
Maher Abu Sabha, director-general of the Border Crossings Administration in Gaza, said that Egyptian authorities told them to close the crossing from both sides.
A limited number of travellers have been able to leave Gaza during the past few days because of a breakdown of computers on the Egyptian side of Rafah crossing.