President Abed Rabbo Mansour Hadi left just hours after the rebels' own television station said they seized an air base where US troops and Europeans advised the country in its fight against al-Qaida militants.
That air base is only 60 kilometres away from Aden, the port city where Hadi had established a temporary capital.
The five officials spoke to The Associated Press on condition of anonymity as they weren't authorised to brief journalists.
Witnesses said they saw a convoy of presidential vehicles today leaving Hadi's palace, located at the top of a hill in Aden overlooking the Arabian Sea.
The advance of the Shiite rebels, known as Houthis, threatens to plunge the Arab world's poorest country into a civil war that could draw in its Gulf neighbours.
Already, Hadi has asked the United Nations to authorise a foreign military intervention in the country.
Already, military officials said militias and military units loyal to Hadi had "fragmented," speeding the rebel advance.
They said the rebels were fighting Hadi's allied forces on five different fronts today.
Early today, Al-Masirah reported that the Houthis and allied fighters had "secured" the al-Annad air base, the country's largest.
It claimed the base had been looted by both al-Qaida fighters and troops loyal to Hadi.
The reported Houthi takeover of the base took place after hours-long clashes between rival forces around the base. The US recently evacuated some 100 soldiers, including Special Forces commandos, from the base after al-Qaida briefly seized a nearby city. Britain also evacuated soldiers.
