PORT-AU-PRINCE, Haiti — First the gangs blocked the roads to Haiti’s capital. Then they attacked the airport. Now they have breached the city’s main port, cutting off the capital from one of its last remaining lifelines for food and supplies as the country teeters toward collapse.

On Wednesday night, dozens of gang members stormed the most important port terminal in Port-au-Prince, looting containers, damaging the port’s security apparatus and forcing the terminal to suspend its operations indefinitely, according to Philippe Coles, the president of Caribbean Port Services, which operates the terminal.

“It’s total paralysis right now,” Coles said in an interview with The Washington Post. “The gangs have the control. They have the upper hand.”

The port’s closure could have disastrous consequences for a capital that is now 80 percent controlled by gangs that, over the past week, have terrorized residents with a wave of killings and kidnappings. Thousands of inmates escaped the two biggest prisons over the weekend. The stench of dead bodies on the streets has prompted some families to leave their homes, human rights activists say. Gang members have encircled the international airport, forcing the suspension of flight operations, and have set fire to police stations. Gang roadblocks nationwide have made it nearly impossible to reach the capital by land. The country’s border with the Dominican Republic is closed. Even Haiti’s embattled prime minister has been unable to return to his country; earlier this week, he flew to Puerto Rico instead.

“Everything has stopped. Medical supplies, food cannot come to Port-au-Prince. Right now nothing can enter by sea, by air or by road,” said one manager in the shipping sector, who spoke on the condition of anonymity because he was not authorized to talk to reporters. “It’s a disaster. Hunger will be the next step.”

On any given day, about 5,000 containers are stored at or transported through the city’s main port, APN, representing about 80 to 90 percent of the traffic of containers to the capital, Coles said. While other ports outside Port-au-Prince remain functional, deliveries to the capital are almost impossible because of the gang roadblocks. In a country that imports most of what it consumes, the port’s containers carry crucial foods — rice, pasta, milk, fresh vegetables — as well as medical supplies.

APN is also serving as a coastal shipment terminal for fuel and other supplies for the north and south, with road access disrupted by multiple gang checkpoints, said Ann Hauge, the manager of an international port that aims to serve Haiti’s southern coast.

“If you were a gang chief you would definitely go after APN,” Hauge said. “It’s the jugular vein of the economy of Haiti.”

Human rights advocates warn that Haiti’s isolation could worsen an already dire humanitarian crisis in the poorest country in the hemisphere.

“These ships are the dry docks with majority food containers,” Mercy Corps, a humanitarian aid group, said in a statement. “If we cannot access those containers, Haiti will go hungry soon.”

Jean-Marc Biquet, the head of Doctors Without Borders in Haiti, said the country faces a major risk of shortages of medication and blood in the coming weeks.

“Very soon, if there isn’t an aerial, port or road opening, all hospital institutions, including Doctors Without Borders, will be unable to continue providing care,” Biquet said.

The armed attack at the port came days after the gangs sabotaged the terminal’s power plant, cutting off its electricity and potentially causing fresh food products to spoil, Coles said. Then, on Tuesday, gang members shot and killed a port security guard while attempting to reach the power plant again.

As the port has faced one attack after another, employees have occasionally taken the desperate measure of stacking containers to create a barricade against the gangs. But Wednesday night, that was impossible.

“The security team was basically under siege,” Coles said. “When you have a group of 50 or 100 thugs coming in with these war guns, these machine guns, they break whatever security force you have.”

Coles said he had not yet assessed the damage or how many containers were breached. He first received reports of gang members roaming the terminal and stealing merchandise at about 3 a.m. Thursday, and the port was not “gang-free” until Thursday afternoon.

Soldiers arrived at the port, but Coles said the army was not “well equipped enough to fight this kind of gang operation.” The police also struggled to fight back against the gangs in the early morning.

“With all this gang activity, the police are spread thin,” Coles said. “They basically had to make a choice — airport or port. I think they chose airport.”

The gang members breached the port terminal in five or six different locations — including the main gate — and by Thursday afternoon the terminal still was not completely secured. The gangs could return. Coles said it might be possible to resume operations at the port within 24 to 48 hours, but only if the police manage to secure it. Even then, it’s unclear when the port would be able to restore power.

“I am sure the losses are going to be quite extensive,” Coles said.

Coles said he spoke to the U.S. Embassy about the suspension of operations at the port. “They told me nothing, unfortunately.”

On Wednesday, few police officers could be seen in the streets of Port-au-Prince. The gangs have set fire to a dozen police facilities in the past week, said Lionel Lazarre, head of the National Union of Haitian Police Officers.

“The police force is on its knees,” Lazarre said. “It can’t even protect its own infrastructure.”

While some supermarkets in Port-au-Prince remain open, many products are running thin, as the gangs disrupt supply routes within the city. Many residents are too afraid to venture out on the gang-controlled streets to find necessary food and water. Supermarkets and small businesses have also been looted.

“Haiti can’t take it anymore,” said Pierre Espérance, director of Haiti’s National Human Rights Defense Network. “Something urgent needs to happen for the ports to reopen and for planes to fly again. … Many people will die if we stay in this situation for the next three days.”