A four-alarm vegetation fire broke out Friday just after noon on Sign Hill/San Bruno Mountain in South San Francisco, immediately threatening homes and a densely populated area. 

The fire, dubbed the Diamond Fire, broke out around 12:15 p.m. and grew almost immediately to four alarms. Pictures and video from the area show the blaze burning to the west of the famed "South San Francisco The Industrial City" sign. As of this writing it's unclear how large the fire has become.

A report on the Citizen app said that police were preparing to halt traffic at Grand Avenue and Chestnut Avenue heading toward Hillside Boulevard just after 1 p.m. As of 1:08 p.m., a house reportedly has caught fire, and crews are attempting to extinguish the flames.

Evacuation orders were issued at 1:10 p.m. for residents of Ridgeview Court, Carnelian Road, Sonja Road, Viewmont Terrace, and Mountain Road.

There were also reports of drones flying in the area which were interfering with the firefight, and South San Francisco police tweeted a message for all drones to cease flying.

We'll update you as we learn more.

SSFFD is working on the fire on Sign Hill. PLEASE DO NOT fly any drones near the area . FD is dropping off fire retardant and is extremely dangerous. Thank you. pic.twitter.com/ZzgxYVVQYb

— SouthSanFranciscoPD (@SSFPolice) October 16, 2020

Better view of the #DiamondFire burning in South San Francisco. @RobMayeda @KTVU @NWSBayArea @CAFireScanner @KPIXtv @abc7newsbayarea @theskylineview pic.twitter.com/BrCUYte3UA

— Antonio Maffei (@AMaffeiWX) October 16, 2020

Better view of the fire currently burning near San Bruno Mountain. Currently 4 alarms and firefighters are enforcing structure protection. @NWSBayArea @KTVU @KPIXtv @abc7newsbayarea @CAFireScanner @nbcbayarea pic.twitter.com/YluTlJehHb

— Antonio Maffei (@AMaffeiWX) October 16, 2020

Update: As of 1:25 p.m., the fire was reportedly mostly extinguished after impacting two residential properties.

#DiamondFire (South San Francisco, San Mateo Co) - Tankers 85, 86 & Copter 106 being released, there is another drone in the area now too per AA140. Fire got onto a couple of residential properties but has all been knocked down. pic.twitter.com/k0CHQfQVs5

— CA Fire Scanner (@CAFireScanner) October 16, 2020