The Kenyan army said Sunday that the majority of the hostages being held by attackers belonging to the Somali-based Islamist group Al Shabab at an upscale shopping mall in this capital have been freed.

The Kenyan army said on Twitter that soldiers had taken over most of the Westgate mall - which several hundred shoppers, many of them expatriate foreigners, had been visiting on Saturday when the terrorist attack began - and continue to advance with the mission of neutralizing the 10 or so terrorists and rescuing all the hostages.

During the course of this final assault, which was begun several hours ago by the Kenyan army, four soldiers had been wounded, the sources said.

The operation was launched at mid-afternoon on Sunday reportedly after a special group of Israeli security forces gained access to the interior of the mall.

An Interior Ministry spokesman told Efe that several explosions were heard inside the commercial complex between 7 and 8 p.m. (1600 and 1700 GMT).

Al Shabab, which in February announced its formal union with Al-Qaeda, had claimed responsibility for the attack in a Twitter post on Saturday, saying that gunmen had killed "more than 100" people inside the shopping center in retaliation for the Kenyan military's participation in the U.N. mission in Somalia.

Kenya's armed forces are backing the Somali government against Islamic militias such as Al Shabab.

Over the 35 hours since the terrorist attack began, the known number of fatalities among mall workers and shoppers rose to 68, while 175 people have been wounded, according to the Red Cross.

The attack began Saturday morning when some 10 armed men speaking Arabic entered the packed mall and opened fire on anyone unable to respond in their language. They reportedly let anyone claiming to be Muslim go free but killed dozens of non-Muslims.

CNN reported Sunday that three of the attackers - all of them about 20 years of age - used to live in the United States, but it was unclear whether any of them were American citizens. EFE