A stench that emanated from a flood-control channel in a Los Angeles suburb and triggered thousands of complaints resulted from chemicals that flowed from a storage yard during a fire and caused vegetation to decay, air regulators said Friday.

The South Coast Air Quality Management District said in a statement it issued notices of violation to four companies and Los Angeles County, which is responsible for maintaining Dominguez Channel.

The notices allege the emissions of hydrogen sulfide caused a public nuisance.

The fire began Sept. 30 at a warehouse property in Carson where two companies stored large amounts of wellness and beauty products, and chemicals including ethanol subsequently flowed into the channel, the district said.

Complaints of a rotten-egg stench began on Oct. 3 and eventually came from thousands of people in at least a half-dozen communities in the area.

The air district sent violation notices to two companies’ whose products were involved, the company that owns the property and its parent company, and LA County. Emails seeking comment were sent to the companies and the county’s Department of Public Works.

Prologis Inc., the parent of the company that owns the property, said in a statement that it was working with the Los Angeles County Fire Department to safeguard the property from storm water runoff and to clean up the fire debris.

The company said the notices do not include any corrective actions for Prologis to take but the company will proactively work with the district to address any concerns.

Notices of violation can lead to civil penalties, voluntary mitigation measures or a civil lawsuit if there’s no settlement.