(CNN) -- A car bomb exploded Wednesday in Egypt's restive Sinai region, killing 10 soldiers and injuring 31 others who were on their way to the capital on leave.
State media reports said a suicide bomber set off the blast as two minibuses carrying infantry soldiers were passing by.
Last month, a suicide bomber blew up a car in Egypt's Sinai, killing four security officers and wounding four others. And a bombing that targeted a military intelligence building bordering on the Sinai, wounded at least six soldiers.
No claim of responsibility has been reported in Wednesday's attack.
Islamist militants have become more active in the Sinai in recent years.
The Egyptian revolution of 2011 that toppled strongman President Hosni Mubarak brought a resurgence of Islamists whom his military regime had repressed for decades.
This included more moderate factions like the Muslim Brotherhood, which swept into power when Mohamed Morsy became President in Egypt's first democratic elections.
But it also included extremists, some suspected of having affiliations with al Qaeda. In the Sinai, they called for the establishment of an Islamist caliphate.
The Egyptian military began cracking down on them again.
In July, when the military ousted Morsy in a coup, Islamist extremists in the Sinai saw it as an attack against Islam and have stepped up their assaults, particularly against soldiers and military installations.
CNN's Saad Abedine contributed to this story