Washington — President Donald Trump pledged on Friday to spare no effort to help Puerto Ricans recover from Maria's ruinous aftermath even as San Juan's mayor, her voice breaking with rage, accused his administration of "killing us with the inefficiency".Mayor Carmen Yulin Cruz implored Trump from afar to "make sure somebody is in charge that is up to the task of saving lives," while the president asserted that US officials and emergency personnel are working all-out against daunting odds, with "incredible" results.Trump's acting homeland security secretary, Elaine Duke, visited the island on Friday, surveying the ravaged landscape by helicopter in an hour-long tour, driving past still-flooded streets, twisted billboards and roofs with gaping holes, and offering encouragement to some of the 10 000 emergency personnel she says the US government has on the ground.READ: Trump defends response to Puerto Rico hurricane disaster Duke tried, too, to move on from the remarks she made a day earlier in which she called the federal relief effort a "good-news story." But on that front, she ran into winds as fierce as Maria."We are dying, and you are killing us with the inefficiency," Cruz said in a news conference. "I am begging, begging anyone that can hear us, to save us from dying."Thousands more Puerto Ricans got water and rationed food Friday as an aid bottleneck began to ease. By now, telecommunications are back for about 30 percent of the island, nearly half of the supermarkets have reopened at least for reduced hours and about 60 percent of the gas stations are pumping. But many remain desperate for necessities, most urgently water, long after the September 20 hurricane.Trump said Puerto Rico is "totally unable" to handle the catastrophe on its own. "They are working so hard, but there's nothing left," he said. "It's been wiped out." He said the government is "fully engaged in the disaster and the response and recovery effort".Trump said he was not aware of Duke's "good-news" remark."I haven't heard what she said," he told reporters. "I can tell you this: We have done an incredible job considering there's absolutely nothing to work with."Solidarity and sympathyYet even in voicing solidarity and sympathy with Puerto Rico, he drew attention again to the island's pre-hurricane debt burden and infrastructure woes, leaving doubt how far Washington will go to make the US territory whole."Ultimately the government of Puerto Rico will have to work with us to determine how this massive rebuilding effort — it will end up being one of the biggest ever — will be funded and organised, and what we will do with the tremendous amount of existing debt already on the island," he said. "We will not rest, however, until the people of Puerto Rico are safe."Earlier he tweeted: "The fact is that Puerto Rico has been destroyed by two hurricanes. Big decisions will have to be made as to the cost of its rebuilding!"Speaking to the press, and taking no questions, Duke said neither she nor Trump will rest until displaced Puerto Ricans are back home, schools, hospitals and clean water are back and the island's economy is moving again. Duke said she is aware people are suffering and "clearly the situation in Puerto Rico after the devastating hurricane is not satisfactory."READ: Jennifer Lopez donates $1m to Puerto Rico relief Trump weighed in on his way to New Jersey for the weekend.He praised his emergency management director, Brock Long, for doing a "fantastic job," pointed out that Duke is serving in an acting capacity and said "she's working very hard."During this season's trio of monster hurricanes — Harvey, Irma, Maria — Trump and his administration have drifted into the perilous territory of premature self-congratulation in the face of unfolding catastrophe, seemingly unmindful of the "Brownie moment" that scarred George W. Bush's presidency.Bush famously told his emergency management director, Michael Brown, "Brownie, you're doing a heck of a job" during what proved to be a tragically inept federal response to deadly Hurricane Katrina in 2005.Trump has repeatedly boasted about the positive reviews he said his administration is getting from Puerto Rico and the US. Virgin Islands for its relief effort, even as people in remote towns struggle to find food, water and other basics. Then Duke said before leaving Washington that the federal relief effort was a "good-news story" because of "our ability to reach people and the limited number of deaths.""Let me clarify," she said Friday upon her arrival in San Juan. She said she meant "it was good news that people of Puerto Rico and many public servants of the United States are working together."Cruz responded, "This is a people-are-dying story."Trump is expected to survey the damage on Tuesday.