CHARLOTTE, N.C. (AP) – Officials say an environmental cleanup company violated a county’s “objectionable odor rule” when it accidentally released a smelly chemical that offended nostrils and caused alarm across Charlotte earlier this month.

The Charlotte Observer reports that the area’s 911 system was flooded with calls on July 14 from people who thought they smelled a gas leak.

In fact, though, a company called Legacy Environmental Services accidentally released a chemical called mercaptan while it was recycling metal tanks.

Mercaptan smells like rotten eggs and is added to natural gas so people can detect leaks.

The Observer reported Friday that Mecklenburg County officials say the release has been classified as a violation and that they’re seeking more information from the company to determine next steps.