Amid the relentless rain brought by an atmospheric river soaking Northern California, a flash flood warning was issued Friday afternoon for San Francisco and parts of San Mateo County where instances of flooding deemed "life-threatening" were occurring.

SAN FRANCISCO - An atmospheric river is bringing heavy rain to San Francisco on Friday, flooding roads across the city. Video shows rising waters in the Marina District and flooded sidewalks along 23rd and Dolores streets. Another video shows cars driving through flooded streets at Henry Adams and Division in the Design District near I-80.

Officials are warning San Francisco residents of dangerous flooding as a powerful atmospheric river propelled by a churning bomb cyclone moves through the region.