Venezuela is once again shuttering gas stations across the country as the chronic shortage of fuel deepens due to ailing refineries and crippling sanctions limiting imports into the country. State oil company Petroleos de Venezuela SA is rationing fuel nationwide, according to a person familiar with the matter, who asked not to be identified because the information isn’t public. The move is partially a result of two of the country’s biggest refineries suffering serious breakdowns in recent weeks amid sweeping U.S. government sanctions banning the sale of gasoline to the country.

The shortage has deepened since Iran sent sent five tankers laden with fuel in May and June to Venezuela, causing U.S. officials to issue warnings to Tehran. No more shipments have been received since. Iran also sent technicians to help improve the reliability of the country’s refineries to little avail. A PDVSA spokesperson declined to comment.

Public transportation has almost disappeared and workers walk even dozens of kilometers to get to their jobs. The situation also presents a logistical crisis, with 90% of commercial goods reliant on road transportation to move around the country.

“Our freight cargo services have slowed down due to lower supply of diesel at fuel stations in five states,” said Jonathan Durvelle, head of the cargo transportation chamber in Puerto Cabello, Venezuela’s biggest port. Some 3,000 affiliated cargo trucks now queue for 12 hours, affecting timely delivery of goods and raising costs.

Three years ago, three to four trucks per day used to haul produce to distribution areas in the center of the country from 480 kilometers (300 miles) away. Now, only two or three come per week, according to Ferraz.