In an apology on national TV, Chipotle CEO and founder Steve Ells said he is "deeply" sorry for the recent spate of food poisoning outbreaks at the restaurant chain.

Since the reports began coming out last month of people becoming ill after eating at the Mexican grill's outlets, the company's stock has plunged 20 percent, and it has warned that same-store sales could fall for the first time in its history this quarter. The Centers for Disease Control and Prevention has been working with local authorities in nine states to investigate the issue, but has not found the source of the problem.

Speaking on NBC's "Today" show on Thursday, the embattled CEO called the problem "a very unfortunate incident" and vowed to put procedures in place to regain consumers' trust.

"The procedures we're putting in place today are so above industry norms that we are going to be the safest place to eat," he said.

A separate outbreak in Boston that impacted up to 120 people, most of them students, appears to be due to a different pathogen — norovirus — and has been addressed by completely sanitizing all surfaces and having all employees to be tested for the virus.

Here are the actions Ells said Chipotle is taking to address food safety across the country:

  • The impacted restaurants were closed "out of an abundance of caution."
  • All 64 of Chipotle's ingredients were tested as well as surfaces at those restaurants. There were "thousands and thousands of tests" that were run, he said. All came back negative for E. coli.
  • The delivery, handling, cooking, and serving were also investigated.
  • Chipotle is developing new and better food safety standards that are above the industry norm.

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