Friday's raid on town of Bulo Marer, south of Mogadishu, came hours after the French intervention in Mali.

BBC: Mali Islamists seize town amid French intervention

On Friday, about 50 helicopter-borne French commandos launched an assault on the al-Shabab stronghold of Bulo Marer, where it is believed Mr Allex was being held.

BBC: Somalia's al-Shabab 'to kill' French hostage Denis Allex

At least 17 al-Shabaab fighters and two French soldiers died in Friday's mission in the village of Bulo-Marer, about 75 miles (120 kilometers) northwest of Mogadishu.

CNN: STORY HIGHLIGHTS

On Friday, about 50 French commandos launched an assault by helicopter on the al-Shabab stronghold of Bulo Marer, believing Mr Allex was being held in the town.

BBC: Denis Allex: French agent 'killed' by Somalia al-Shabab

The racket of helicopter blades and volleys of gunfire startled Bulo Marer town residents out of their sleep Friday night, when French paratroopers descended on the camp.

CNN: STORY HIGHLIGHTS

Then, French commandos went into action in Somalia, swooping on the town of Bulo Marer in an attempt to free Denis Allex, who was kidnapped in July 2009.

BBC: UK troops to assist Mali operation to halt rebel advance

Al-Shabab said it had advance warning of the attack and Mr Allex - a codename for the French intelligence agent - was not in Bulo Marer at the time.

BBC: Denis Allex: French agent 'killed' by Somalia al-Shabab

The skirmish in Bulo Marer, about 75 miles northwest of the capital Mogadishu, ended with a French soldier and 17 Islamist fighters dead, according to the French Defense Ministry.

CNN: U.S. supported France's failed hostage rescue in Somalia