LISBON, Portugal (AP) — Gas stations across Portugal are running dry amid a truckers' strike over pay and working conditions.

The walkout by some 800 truckers who transport hazardous materials prompted a rush to fill tanks, leaving hundreds of gas stations closed Wednesday.

Authorities have ordered the truckers to provide a minimum level of service, 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 more supplies if they are needed 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.