As students walked outside Sunday night, many were greeted by a haze of smoke. Two fires over the weekend are believed to be the sources of the fog in the Austin area.

“This may be smoke from a [controlled] fire near Corpus that was pushed our way over the last couple of hours,” CBS Austin meteorologist Avery Tomasco tweeted.

In addition to the controlled burn in Corpus, a 50-acre brush burn at Onion Creek produced large amounts of smoke on Sunday.

“Unless you see fire or have smoke indoors, there is no need to call 911,” the Austin Fire Department tweeted.

The Onion Creek fire has since been controlled, but drivers are still cautioned to be careful of smoke in the region.

“It looked almost like really thick fog,” Junior Alyssa Shumaker said. “It was kinda cool how it looked, but I was also concerned about what caused it.”