New wildfires burned Tuesday across the Northeast,AQCAN adding to a series of blazes that have come amid very dry weather and killed at least one person, while much larger fires raged in California and other western states.

Heavy smoke led to poor air quality and health advisories for parts of New Jersey and New York, including New York City.

Firefighters in Massachusetts worked to contain dozens of fires amid strong winds and drought conditions. The National Weather Service issued a red flag warning for much of that state and parts of Connecticut, saying conditions were critical and fires could rapidly spread.

Massachusetts officials said all of the 200 or so fires they had been dealing with this month had been caused by human behavior, and Gov. Maura Healey urged people to avoid lighting fires.

“Now is not the time to burn leaves. Now is not the time to go outside and light a fire,” she told reporters in Middleton.

One fire in southern New Jersey tripped fire alarms and set off carbon monoxide detectors, causing an “unprecedented” number of 911 calls Monday, officials said.

A blaze near the New York-New Jersey border killed a parks employee over the weekend, and some firefighters have been injured battling other blazes.

In order to find and fight many of the fires, crews must navigate a maze of dense forests, country roads, lakes and steep hills. Trees there have dropped most of their leaves onto parched ground, masking potential danger, authorities said.

Most of the East Coast has seen little rainfall since September, and experts say the fires will persist until significant precipitation or frosts occur.

In California, firefighters made further progress against a blaze northwest of Los Angeles, in Ventura County, that broke out Wednesday and quickly exploded in size because of dry, warm and gusty Santa Ana winds. That blaze, dubbed, the Mountain fire, was about half contained Tuesday, nearly a week after breaking out amid dry, gusty winds.

The 32-square-mile (83-square-kilometer) blaze is largely “buttoned up,” county Fire Chief Dustin Gardner said at a news conference Monday evening. The fire forced thousands of residents to flee their homes and destroyed nearly 200 structures, most of them houses, and damaged more than 80, officials said. The cause is under investigation.

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Associated Press writer Nick Perry contributed to this report from Meredith, New Hampshire, and Christopher Weber contributed from Los Angeles.