US President Donald Trump defended the government relief response to hurricane-ravaged Puerto Rico on Tuesday and promised to visit the island next week.
Trump also said that he would travel to the US Virgin Islands, another American territory in the Caribbean that was slammed by a pair of powerful storms.
"Both have been devastated, and I mean absolutely devastated," the president told reporters at a joint press conference with Spanish Prime Minister Mariano Rajoy.
"Puerto Rico got hit by two hurricanes... And they were among biggest we've ever seen."
Relief efforts were complicated by the fact that it is an island, which now faces a "long and very, very difficult restoration process," Trump said.
Before Maria struck last week, Puerto Rico and the US Virgin Islands were also hit by Hurricane Irma - which killed at least 112 people, 72 of whom were in Florida, according to an updated death toll released Tuesday.
Rejecting accusations Puerto Rico has not received the same level of assistance as storm-hit US states Florida and Texas, Trump said a "massive relief effort is underway."
Trump said he had ordered all relevant agencies and the military to do "everything in their power" to help residents of Puerto Rico.
"We are unloading on an hourly basis massive loads of water and food and supplies for Puerto Rico," the president said, adding that he would visit there on Tuesday.
US officials said 16 ships - US Coast Guard and US Navy vessels - were taking part in the relief effort, bringing generators, food and water.
The USNS Comfort, a 1,000-bed hospital ship based in Virginia, was also headed for Puerto Rico.
'Life or death'
Most of the 3.4 million people in the overwhelmingly Hispanic US territory in the Caribbean are without running water, electricity and communications following Hurricanes Irma and Maria.
Food, water and fuel are scarce, leading Puerto Rican officials and residents to issue increasingly desperate appeals for help.
"It's life or death," said Carmen Yulin Cruz, mayor of the capital San Juan.
"People are really dying," the mayor of the city of nearly 400,000 people told CBS News. "There are people that have had no food and no water for 14 days."
Trump has come under fire for tweeting repeatedly over the weekend about American football players kneeling during the national anthem while failing to mention Puerto Rico.
Singer Marc Anthony, who was born in New York of Puerto Rican parents, told Trump in a tweet with an expletive thrown in to stop talking about the National Football League and "do something about our people in need in #PuertoRico."
"We are American citizens too," Anthony said.
Appealing for "swift action" from the Trump administration and US Congress, Puerto Rico Governor Ricardo Rossello also felt the need to issue a reminder - twice - that Puerto Ricans are US citizens.
Rossello stressed that the devastation from the "unprecedented disaster" was "vast."
"Make no mistake - this is a humanitarian disaster involving 3.4 million US citizens," he said. "We will need the full support of the US government.
"People cannot forget that we are US citizens - and proud of it."
In a video teleconference call with Rossello, Trump assured him that "America stands with the people of Puerto Rico," and promised continued federal assistance for Puerto Rico and the US Virgin Islands, the White House said.
It said that during a briefing with senior administration officials on the federal response, Trump "stressed that his top priorities are life-saving and life-sustaining efforts in the affected areas."
While they are American citizens, residents of Spanish-speaking Puerto Rico are not allowed to vote in US presidential elections and the island has only a non-voting representative in the US Congress.
Trump dismissed charges he neglected Puerto Rico while spending too much time on the anthem controversy.
"I wasn't preoccupied with the NFL," he said. "Not at all. I have plenty of time on my hands. All I do is work."
Ben Sasse, a Nebraska senator from Trump's Republican Party, was among those urging more federal government help for stricken Puerto Ricans.
"The crisis for these Americans needs more attention - and more urgency from the executive branch," Sasse said in a tweet.
The Federal Emergency Management Agency has shrugged off the criticism and said there are more than 10,000 federal staff on the ground in Puerto Rico and the US Virgin Islands providing help.
Paul Ryan, the Republican speaker of the US House of Representatives, pledged more congressional assistance.
"This is a humanitarian crisis," Ryan said. "This is our country and these are our fellow citizens."