A Sunnyvale preschool was told to shelter-in-place due to a hazardous materials investigation on Monday, officials said.
Police and fire officials said someone dumped a number of five-gallon buckets into a dumpster at the AppleSeed Montessori School on Dunford Way. Shortly after, smoke was seen billowing from the dumpster, authorities said.
Sunnyvale fire crews were called to respond to the scene just before 4 p.m. Monday. Officials said just before 5:30 p.m. parents were being allowed to pick up their children on the east side of the school.
Crews were wrapping up the investigation just before 7 p.m. and reported air readings they did were negative.
Several streets in the area were temporarily blocked during the investigation.
No other information was immediately available.