San Francisco’s air quality watchdog has served the former Russian consulate a notice of violation for burning “garbage” without permission, the local CBS television station reports.

Plumes of black smoke were seen coming out of the consulate building on Sept. 1, a day before it was set to close on the orders of the U.S. State Department.

The U.S. State Department ordered Russia to vacate its San Francisco consulate and scale back activities at annexes in Washington D.C. and New York by September after Russia told the U.S. diplomatic to cut its staff by hundreds of people.

Russia’s Foreign Ministry spokeswoman Maria Zakharova said the smoke coming from the consulate was the result of efforts to “preserve the building,” including “closing the windows, lowering the curtains, cutting off the water, turning off the lights, closing the doors, throwing away the garbage.”

But some media reported Russian diplomats might be burning documents before vacating the property.

“We’re issuing a violation for burning garbage,” Bay Area Air Quality Management District (BAAQMD) spokesman Ralph Borrmann was quoted as saying Tuesday.