(CNN) -- A Red Cross official who had worked in Iraq, Sudan, Yemen and Gaza was shot dead Wednesday in Libya, the organization said.
Gunmen attacked the vehicle of Michael Greub, 42, around midday as he left a meeting with two colleagues in the Mediterranean Sea city of Sirte, the International Committee of the Red Cross said.
Libya's state-run news agency, LANA, reported that masked gunmen in a car with tinted windows opened fire and killed Greub, who headed the Red Cross' unit based about 150 miles (245 kilometers) away in Misrata.
His driver and an escort escaped unharmed, LANA said.
"We are devastated and outraged," ICRC Director-General Yves Daccord said in a statement. "Michael was a devoted humanitarian who spent many years of his life helping others."
The Red Cross said Greub, a Swiss national, had been with the international aid organization for the past seven years. He moved to his latest stop, Misrata, in March.
Sirte was the hometown of Moammar Gadhafi, Libya's longtime leader until he was ousted and killed in October 2011 in a revolution. Since that time, Islamist extremist groups have become increasingly active in the coastal city.
The Red Cross has had a permanent presence in Libya since 2011, working with the Libyan Red Crescent to administer first aid and help those injured or displaced by violence.
CNN's Jomana Karadsheh contributed to this report.