A fire at a homeless encampment in the Mission Bay neighbor of San Francisco was quickly extinguished by firefighters Wednesday morning, but caused a huge plume of smoke. The fire broke out just before 7 a.m. at the encampment at Seventh and Berry streets and burned several tents clustered in the area. By 7:30 a.m., firefighters had the blaze out. There were no immediate reports of injuries and it was unclear what sparked the blaze.