Mankato (KMKO)-Mankato firefighters responded to a grass fire last night.  Crews from the Department of Public Safety Fire Division were called about 7:30 pm to deal with the fire between Highway 14 and Highway 169 on the east side of the Minnesota River.  Fire officials tell KMKO news the blaze covered an area approximately 1,000 feet by 100 feet.  Three trucks and a pickup containing a small booster tank were employed.  The fire was out and crews left the area about 9:30 last night.