TREBES, France (AP) — France's top security official says a heroic officer who swapped himself for a hostage during an attack on a supermarket has died of his injuries.

Interior Minister Gerard Collomb wrote in a tweet early Saturday that Col. Arnaud Beltrame had "died for his country."

Beltrame offered himself up unarmed to the 25-year-old attacker in exchange for a female hostage. He managed to surreptitiously leave his cellphone on so that police outside could hear what was going on inside the supermarket. Officials said once they heard shots inside the market they decided to storm it, killing the gunman.

Beltrame was grievously injured, and his death raises the toll from the attack to four.

The Islamic State group claimed responsibility for the attack, the deadliest since Emmanuel Macron became president last May.