WINDSOR, Calif. (AP) — A firefighting air tanker unintentionally dropped retardant Thursday, turning cars and lawns in a Northern California neighborhood a reddish-pink before workers cleaned it up.

The Santa Rosa Press Democrat reports ( ) that a Cal Fire air tanker was returning from a grass fire when the pilot released about 100 gallons of water mixed with Phos-Chek over the Sonoma County town of Windsor.

Phos-Chek is a fertilizer that both stops fire and encourages growth.

It's not clear why the pilot dropped the material during the landing approach.

Firefighters washed the vehicles and cleaned the road. Windsor city staff worked to prevent retardant from slipping into storm drains.

Cal Fire Division Chief Ben Nicholls said the material is safe for roofs. He said that lawns and gardens may grow a little greener.