NEW YORK (AP) — Oil prices are tumbling for the third straight day and natural gas futures are accelerating a sell-off amid growing concerns about the weakening U.S. economy.

Light, sweet crude for August delivery is down $3.50 at $131.10 a barrel on the New York Mercantile Exchange in extremely volatile trading. Oil is now down about $14 in the last three days.

Natural gas prices are also plunging.

Natural gas is trading down 82.6 cents at $10.572 per 1,000 cubic feet. It has tumbled more than 20 percent since its peak before the Fourth of July.