The explosion, which killed three people and injured seven, occurred in the town of Pavshino Saturday at 9:10 a.m. Moscow time (5:10 a.m. GMT).
It completely destroyed the plant, and damaged residential buildings within a six-kilometer (3.7 miles) radius of the scene.
"All schools and pre-school establishments [in the district] will be closed within the next three days, and then we will see how the situation develops," a spokesman for the Education Ministry said.
Moscow regional authorities said rescuers and emergency services were working at the scene.
The Federal Service for the Oversight of Consumer Protection and Welfare said it was considering an emergency preventive Hepatitis A vaccination program for all children under 14.
The Moscow Region authorities said the families of those killed in the blast will receive a one-time compensation of 150,000 rubles ($5,500).
Emergency officials said earlier a high gas concentration inside the plant could have triggered the explosion, without elaborating on its source.
"One of the factories in the area of Krasnogorsk could have dumped explosive substances [into the sewage systems] - acetone, benzene or some other inflammable liquids," said Alexei Panteleyev, deputy governor of the Moscow Region.
Panteleyev said 19 enterprises working in the region were being investigated.
He said 260,000 people were left without water, and that drinking water was being supplied by trucks.
Authorities said that water supplies would be restored Monday and measures have been taken to prevent a sewage spill into the Moskva River, located 150 meters (492 feet) from the scene.
Three victims of the explosion are in hospital with serious burns and head injuries, but doctors said their lives were out of danger. The others were treated and released.
The explosion damaged 19 residential buildings in the region, shattering windows and doors. Roofs and walls were seriously damaged in five buildings.
