Some gas stations near the Otay Mesa border crossing and others south of Tijuana temporarily shut down their diesel pumps yesterday because they ran out of the fuel, while other stations experienced long lines of trucks and buses waiting to purchase what was available.

Gas station managers and shift supervisors said the Pemex plant in Rosarito Beach is distributing fuel, but in limited quantities.

Meanwhile, there is high demand for inexpensive fill-ups from U.S. drivers and those who commute across the border. Fuel in Mexico is subsidized by the government and costs up to 50 percent less than in San Diego.

Public transit, which was in danger of coming to a halt in mid-June when shortages first occurred, is once again feeling the greatest effect.

Arturo Aguirre, manager of Transportes Calfia, the city's largest public-transport firm, said as many as 40 percent of buses from 11 companies are idled. His company normally operates 1,200 buses that carry 350,000 riders every day.

None of the stations surveyed yesterday had received enough fuel. Pemex has not offered an official comment.

Sergio Martínez, the manager at a station south of Tijuana, said he receives a little more than 15,000 gallons per week, enough for two days.

A tanker ship resupplied the Pemex distribution plant in Rosarito Beach almost two weeks ago, but that has not been enough to meet demand.

Omar Millán González is a contributor to the Union-Tribune's Spanish-language weekly Enlace.