You may have heard street sweepers on Saturday night. Don't worry, you didn't hallucinate.

A big rig sprung a leak Saturday afternoon on Oak Street at about 2pm, causing a big traffic jam near Masonic. DPW was called in to save the day, spreading sand all over the spill to reduce the fire hazard caused by the oil. 

The result? Fortunately, no fires. Less fortunately, the Upper Haight experienced an impromptu dust storm. Saturday afternoon, the air was thick with dust, and two days later, most surfaces anywhere near an open door or window are still covered in a fine layer of white dust. 

Thanks to Meghan Arnold for alerting us on Twitter:

Seriously what the hell happened on Haight today? Playa dust? @uppercasing @SF311 pic.twitter.com/xT8bEVCntJ

— Meghan Arnold (@MeghanCArnold) January 11, 2015

Apparently a big rig leaked oil down cole and haight and they had to lay sand to reduce fire hazard. Crazy! @uppercasing @abc7newsBayArea

— Meghan Arnold (@MeghanCArnold) January 11, 2015

@MeghanCArnold Did it feel like Burning Man?

— Christin Evans (@christinevans) January 11, 2015

Later that night, DPW sent in street sweepers to address the sand, and they were spotted as far as Haight Street. 

There were no injuries or collisions due to the spill, although police were called in to direct traffic away from the hazard.