More than a week after Hurricane Maria hit Puerto Rico, the island is still mostly without power, and the widespread devastation and shortages of food and water have left residents of the island reliant on federal relief for survival.

But many people feel that the promised federal relief has failed to materialize. And in the humanitarian crisis facing Puerto Rico more than a week after Hurricane Maria struck, the widespread loss of power and dangerous conditions have crippled emergency medical care on the island.

According to a Federal Emergency Management Agency update from Tuesday night, thousands of federal staff, including more than 500 FEMA personnel, are already operating response and recovery operations in Puerto Rico and the U.S. Virgin Islands, and federal agencies are promising thousands of more workers and ships of aid and supplies. But on an island where 3.4 million remain without power and running water, complaints have rolled in that accuse the federal response of being too slow or too negligent of areas other than the capital city.

One of the most dangerous threats from the damage is to hospitals on the island. Power has been restored to a major hospital in San Juan, according to FEMA, and the U.S. Department of Health and Human Services is setting up makeshift hospital units. But CBS reported that only 21 of 69 hospitals have power or fuel, and two people on life support already died when their hospital ran out of fuel. CNN reports that a hospital in San Juan where 12 children depend on ventilators to survive has only a limited amount of fuel for its generators.

To help with Puerto Rico’s pleas for medical assistance, defense officials announced Tuesday night the military was planning to send the USNS Comfort hospital ship, although it might not be ready to deploy for another week. More than 150 patients have also already been evacuated from Puerto Rico and the U.S. Virgin Islands to the mainland, according to FEMA. And the military is sending other aircraft to aid in relief efforts.

Meanwhile, a lack of power and running water makes it difficult to keep sanitary conditions or do even basic medical tasks. A surgeon told Reuters that the cardiovascular center where he worked dripped with condensation in the heat and that most of its patients had been evacuated to other facilities. Some had to remain, though, because the center could not reach the families. Communications are still spotty on the island. “If you are sick in Puerto Rico,” the doctor told Reuters, “the best thing is to get on a plane and abandon the island.”

But flights, too, are hard to come by. A Puerto Rican reporter for Telemundo PR tweeted that all flights are oversold and the airlines are deciding who gets on what flight. Reuters reported that those without tickets might not be able to buy any for another week. Damage to the radar and aviation equipment has limited the number of flights to and from the island, according to CNN. And on Monday there were only 10 commercial flights between San Juan and the mainland U.S. Many commercial airlines are dedicating their planes to transporting relief workers and supplies. Two airlines, CNN reports, are solely operating relief flights.

But despite the aid, many people are comparing the federal relief efforts in Puerto Rico to those for the recent hurricanes Harvey and Irma in Texas and Florida and finding it severely lacking. Fewer people have been dispatched to help, but President Trump and federal officials also counter that the logistic difficulties of reaching the island have made it harder to meet the demand for aid as quickly.

Meanwhile, Congress is working on an aid package, which House Speaker Paul Ryan said would come in October.

Trump, who failed to mention Puerto Rico for days in which he instead tweeted about protesting professional athletes, will visit the island on Tuesday, almost two weeks after the hurricane struck.