“They’re not letting us move at all,” said Danny Custodio, 37, who stood in the atrium of the convention center with his cousin on Thursday afternoon. “We’re in a crisis. Just open up the port so I can get what I need to get and take it where I need to take it.”

Officials said that some containers were sitting in the port because businesses, many still shuttered, were not in a position to receive supplies. Warehouses were damaged. And apart from generators, no power source was available to keep perishable goods cold.

About 600 containers did leave the port on Wednesday, up from 450 a day earlier, said Omar Marrero, the executive director of the Puerto Rico Ports Authority. He said that he expected that as many as 1,200 could leave on Thursday.

Throughout Puerto Rico, residents say they have yet to see their mayors distribute aid. In Ponce, people who waited overnight to buy an allotted two small bags of ice had to repeat the act each night because, without electricity, the previous day’s purchases had melted.

Hector Marquéz, 66, said he goes to the ice line every day at 3 a.m. to be ready for its 7 a.m. opening. “Have you seen a single tarp over anyone’s house? People lost their roofs. Where are the tarps?” Mr. Marquéz said. “They haven’t brought anything here.”

He rattled off a list of what he could not find: bottles of water, gas canisters to light stoves, food.

“Whatever little bit you had is running out,” he said. “The trucks with food do not come. No trucks come with anything. You go to the supermarket, and it’s almost empty.”