California will require millions of health care workers and state employees to show proof of a COVID-19 vaccination or get tested weekly, announcing a broad measure this week to try to slow rising coronavirus infections in the nation’s most populous state, mostly among the unvaccinated.

The new rule, to take effect next month, is the latest example of California and politically progressive cities nationwide cracking down on a virus that has upended life since March 2020. New York Mayor Bill DeBlasio announced a similar plan Monday that requires 340,000 city employees, including teachers and police officers, to show proof of vaccination or undergo weekly testing.

A lightning strike likely ignited a 2020 wildfire in California’s Sierra National Forest, but the U.S. Forest Service said Friday it could not determine an official cause of the fire.

September’s Creek Fire burned 600 square miles and spread so quickly that hundreds of Labor Day holiday campers had to be rescued by a series of harrowing helicopter flights. All 214 campers were delivered safely.

Investigators did not rule out arson and lit cigarettes as the cause, but said there were no illegal marijuana grow sites nearby that could have started the fire. Forest service officials said an “undetermined” status is not uncommon with a fire this complex.

Pacific Gas & Electric reported to California utility regulators that its equipment may have been involved in the start of a fire burning in the Sierra Nevada that is threatening hundreds of homes.

PG&E said in a report Sunday to the California Public Utilities Commission that a repairman responding to a circuit outage on July 13 spotted blown fuses in a conductor atop a pole, a tree leaning into the conductor and fire at the base of the tree.

The utility said its system showed around 7 a.m. that the Cresta Dam off Highway 70 had lost power but because of the steep, rough terrain, the worker sent to check it couldn’t reach the area until nearly 5 p.m.

It may have been around 2017 when a true sense of urgency donned on insurers, public officials, residents and regulators in wildfire-prone California, as fires destroyed or damaged more than 10,000 structures in the state, a higher tally than the previous nine years combined.

In terms of property damage, 2017 was the most destructive wildfire season on record in California at the time, with 9,133 fires burning more than 1.2 million acres, and it was after 2017 that the word “mitigation” seemed to appear more prominently and more often in public messaging about wildfires – along with news of warnings about rising homeowners insurance rates, increasing non-renewals, and of course climate change.