A grass fire that has burned more than 200 acres between Tracy and Livermore shut down westbound Interstate 580 Thursday afternoon.

The Midway Fire broke out at 2:51 p.m. Thursday near Patterson Pass Road and Midway Road in Alameda County south of the Altamont Pass, according to Cal Fire.

Cal Fire named the blaze the Midway Fire. It broke out around 2:51 p.m. in the area of Patterson Pass and Midway roads near Altamont, between the cities of Livermore and Tracy. As of 4 :15 p.m., the fire had grown to 280 acres, according to Cal Fire.