The video drove shares of the fast casual chain down 4.5% Thursday, just days after the stock took a hit from reports of a norovirus outbreak at one of its locations in Sterling, Va. Chipotle’s stock price is now valued at $356 a share, its lowest point in four years.

Crowd-sourcing website iwaspoisoned.com suggested that the total number of sickened customers in Sterling was above 100. But health officials have so far only confirmed 60 ill consumers and one case of norovirus, also referred to as the”winter vomiting bug.”

As for the rats, a spokesperson for the company told Fortune in an e-mail it was “an extremely isolated incident but of course it’s not anything we’d ever want our guests to encounter.”

Chipotle’s recovery from its last food safety crisis in 2015, an E.Coli outbreak, has certainly hit a snag.

Meanwhile, Bill Ackman‘s losses from the incidents over the past two days have deepened. Ackman, who is the company’s largest shareholder, has seen the value of his stake slide $112.4 million since early Tuesday to about $1 billion.