LISBON, Portugal (AP) — Gas stations across Portugal began to run dry Wednesday as a truckers’ strike over pay and working conditions entered its second day.

The ongoing walkout by some 800 truckers who transport hazardous materials prompted a rush to fill tanks has left hundreds of gas stations closed.

Authorities have ordered the truckers to supply essential deliveries, in accordance with a law that requires workers in important sectors to provide a minimum level of service.

That means truckers are still delivering gas to airports, hospitals and emergency services as well as 30% of average daily supplies to gas stations in the Lisbon, the capital, and Porto, the second-largest city.

The government says it may demand an increase in the minimum volume of supplies if such a step is required to avoid severe economic damage.

The truckers want higher pay and shorter working hours. A meeting between employers and the truckers’ trade union broke up without agreement late Tuesday.