The UN children's agency chief offered a dire assessment Sunday of the chaotic situation in Haiti, saying it was "almost like a scene out of 'Mad Max,'" which depicted a violent and lawless post-apocalyptic future.

"Haiti is a horrific situation," UNICEF executive director Catherine Russell told CBS talk show "Face the Nation."

"Many, many people there are suffering from serious hunger and malnutrition and we're not able to get enough aid to them," with gangs controlling large parts of capital Port-au-Prince as well as key roads leading elsewhere.

The situation is "the worst that anyone has seen in decades," she said.

"It's almost like a scene out of 'Mad Max.' That's what it seems like," Russell said of the 1979 film.

Haiti, already hit by drought, natural disasters and a weak government, has seen "the near-collapse of basic services," a recent United Nations report warned.

That has left millions vulnerable as they await the formation of a transitional governing council to take power after unpopular Prime Minister Ariel Henry announced his resignation Monday under pressure.

The challenges facing foreign aid workers -- some of whom have been attacked or kidnapped for ransom -- were underlined Saturday when gangs looted a Unicef shipment intended to provide relief for suffering mothers and children.

"Today, Unicef's container, containing crucial supplies for maternal, neonatal and child health, was looted at Port-au-Prince's main port," the agency's Haitian account posted Saturday on X. 

"This incident occurred at a critical moment when children needed them the most."

As life grows more difficult for Haitians and foreigners, a US State Department spokesperson said Sunday that a chartered flight with more than 30 US citizens on board had landed in Florida after departing Cap-Haitien earlier in the day. 

"We will continue to assist US citizens as long as commercial options remain unavailable and the security environment permits us to do so," the spokesperson said.  

Non-essential US embassy staff were evacuated last week.

Haiti has been convulsed for two weeks by a gang uprising, as brutal and well-armed groups -- their numbers swollen after an attack on two prisons freed thousands of inmates -- sought to topple Henry.

On Sunday, a curfew was extended until Wednesday in the Ouest department, which includes Port-au-Prince. A state of emergency is set to end 3 April. 

Meantime, efforts are continuing to organize a Kenyan-led security mission to back up the Caribbean island's overwhelmed police force.