Nairobi. Heavy and sustained gunfire has been heard from the Nairobi mall where Somali group al-Shabab are holed up, holding an unknown number of civilians hostage.Two al-Shabab fighters have been killed in the ongoing military raid to end the standoff and nearly all hostages have been freed, Kenya’s Cabinet Secretary for the Interior Ole Lenku said on Monday."We don’t want to give you a definitive position on when we think the process will come to an end, but we are doing anything reasonably possible, cautiously though, to bring this process to an end,” Lenku told a news conference.Black smoke has been seen rising and several blasts have been heard in the area, two days after al-Shabab fighters stormed the mall.Lenku said a fire inside the mall was the work of the fighters, but that it would soon be extinguishedHe said that Kenyan forces were in control of all floors of the mall, and that "the terrorists are running and hiding in some stores [...] there is no room for escape”. Television images on Monday showed troops in camouflage running to new positions, while an armoured personal carrier was also seen shifting position.Journalists and their cameras have been moved and no longer have a clear sight of the mall, but can see its perimeter."It is us who caused the explosion, we are trying to get in through the roof,” one security official, who asked not to be named, told the Reuters news agency at the scene. There was no official comment.Al Jazeera’s Catherine Soi, reporting from the vicinity of the mall, said that the concern was that the fighters would not allow themselves to be apprehended, and that they might harm any remaining hostages."They went in there with a suicide mission, they knew that it was very difficult for them to get out alive. [...] The concern really is the hostages. The ministry says that they have been able to evacuate most of the people in that mall ... more than 1,000 people have been evacuated [since the siege began], but the concern is with the hostages [still in the building],” she reported.Meanwhile, the International Criminal Court (ICC) announced that it was adjourning the trial of Kenya’s Deputy President William Ruto on charges relating to violence following elections in 2007.The court said Ruto would be excused from the trial, which began earlier this month, for a week to return to Nairobi to help deal with the crisis.On Sunday, Kenyan security forces claimed to have rescued most of the hostages, but an unknown number remain trapped inside.