Gas prices are spiking after the biggest US refinery shuts down

Gasoline prices are surging again on Thursday amid refinery closures in Texas caused by Hurricane Harvey.

Gas futures for September delivery are up 12% to 2.11 per gallon at 10:40 a.m. ET. In their eighth straight day of gains, futures are on their longest rising streak in four years, according to Bloomberg. Futures for October delivery also gained.

Prices at the pump are also higher. The AAA's average national gas price at 3:43 a.m. ET on Thursday was $2.449 per gallon, up from an average price of $2.348 per gallon last week.

Motiva's refinery in Port Arthur, which is the largest in the US, shut down Wednesday as flood waters rose. And on Thursday, Colonial Pipeline, which owns the largest pipeline for gas distribution in the US, had to shut down its main line because Gulf Coast refiners were unable to process crude oil, Bloomberg reported.

To help with the gasoline shortage, the Energy Information Administration said Thursday it was releasing 500,000 barrels of oil from its Strategic Petroleum Reserve that keeps supplies for emergencies. The agency said in a statement that it loaned the barrels of both sweet and sour crude to a Phillips 66 refinery in Lake Charles, Louisiana, which has not been affected by Hurricane Harvey.

The Fort Worth Star-Telegram reported that some gas staions in the area might run out of supplies during the Labor Day weekend. Gas stations on the East Coast could also experience shortages following the closure of Colonial Pipeline's conduit, Bloomberg reported. This could send gas prices even higher.