Trbes - A French policeman shot by an Islamist gunman Friday after swapping himself for a hostage in a siege at a supermarket in the southwest town of Trebes is "fighting for his life", President Emmanuel Macron said."He volunteered to take the place of the other hostages and has been very seriously wounded," Macron said in a televised address.The 45-year-old policeman was among a group of officers who rushed to the scene after the attacker, who claimed allegiance to the Islamic State group, stormed the store and fired on shoppers and staff before taking them hostage."He saved lives and honoured his colleagues and his country," Macron said of the officer."He is currently fighting for his life and all our thoughts go out to him and his family."The assailant, identified as 26-year-old Radouane Lakdim, shot dead two people at the supermarket after earlier opening fire on passengers in a car, killing one of them, and injuring a police officer in nearby Carcassonne.Speaking at the scene earlier Interior Minister Gerard Collomb said a police team immediately intervened after the start of the siege at around 11:00."They managed to get some of the people out," he said, but the attacker kept one woman back as a human shield.The heroic officer then offered to take her place and remained holed up with Lakdim while negotiations to end the standoff continued.The officer "left his telephone on the table", to allow police that had surrounded the building in the sleepy town of 5,000 inhabitants listen in, Collomb said."When we heard shots the GIGN (an elite police force) intervened," the minister said, adding that the policeman was "seriously injured".Collomb praised the officer for his "courage" and "act of heroism".An officer from the police SWAT team was also hurt in the operation to kill the gunman.