In this aerial view, a burned neighborhood is seen in Santa Rosa, California on October 12, 2017.

There have been at least two incidents of drones disrupting firefighting activities during the deadly Northern California wildfire disaster, the FAA said Monday.

"We received two reports of incidents in which people flew drones in fire areas," Ian Gregor, a Pacific Division spokesman for the U.S. Federal Aviation Administration told CNBC in an email statement. "We will look into both."

One of the drone incidents took place early last week in the Santa Rosa area, but a second was in the city of Petaluma on Sunday, resulting in an arrest. The wildfires in the Sonoma County/Santa Rosa area started Oct. 8.

The drone incursions come as the death toll in the Northern California wildfires increased to at least 41 people Monday, which includes a driver killed in a water tanker crash in Napa County. In Sonoma County alone, at least 88 people are listed as missing.

The state wildfires in several counties have scorched more than 220,000 acres and destroyed an estimated 5,700 structures, including entire neighborhoods. There also are reports of at least 10 wineries or vineyards damaged or with significant damage in the Sonoma and Napa areas, heart of the state's wine country.

The so-called Tubbs Fire in mostly Sonoma County was 70 percent contained as of Monday afternoon and full containment was expected Friday. More than 24,000 homes are still threatened by the wildfire, although rain is forecast for Thursday and could bring welcome relief to the region.

The mayor of Santa Rosa, Chris Coursey, estimated that damage in the city exceeded $1 billion. The cause of the Tubbs fire is still under investigation.

Meantime, authorities say hobbyist drone incursions on wildfires pose a safety risk to firefighting aircraft battling the disaster and jeopardizes the safety of residents and crews on the ground.

"Over the years, we have seen this problem become a trend," said Cal Fire spokesman Daniel Berlant. "When drones are flying in the same airspace we're trying to use firefighting aircraft, like helicopters and air tankers, for the safety of our pilots we've got to pull those aircraft out of the sky and land them."

Added Berlant: "The potential for a fire to grow larger and do more damage during the time we can't use firefighting aircraft while that drone is in that area exists. That's why it's critical that we educate and ensure that the public is not flying their drones over our aircraft or over fires."

The Petaluma Police Department announced Sunday a drone flew over Petaluma Airport and halted Cal Fire helicopters from flying out in response to fires in Sonoma and Napa counties.

According to the police, a 24-year-old resident was questioned about the incident, arrested and "stated he did not realize it was illegal."

The FAA official said a drone pilot who "recklessly interferes with firefighting or other emergency response operations" is subject to civil penalties from the FAA of up to $20,000 per violation.

Nationally, drone incursions during wildfires are growing as more people get their hands on the unmanned devices capable of capturing video or photos. From 2015 to 2016, the incidents of private drone incursions over or near wildfires jumped from around 12 cases to 42 reported instances, according to the Interior Department.

In July, firefighters battling the Williams Fire in the northern portion of Arizona were forced to delay using a helicopter for water drops after an unauthorized drone was spotted. Similarly, there were several other cases of private drones causing problems for crews fighting Arizona's Pinal Fire in May.