ATLANTA (AP) — A Delta Air Lines flight returned to the Atlanta airport soon after taking off Monday when crew members reported a smoky haze inside the cockpit, according to federal officials.

Delta Flight 876 to Columbia, South Carolina, returned safely to Hartsfield-Jackson International Airport on Monday morning “after the crew reported possible smoke in the flightdeck,” the Federal Aviation Administration said in a statement.

The FAA said it’s investigating the incident, which came after a Delta plane flipped over last week while crash landing in Toronto, injuring 21 people.

Delta released a statement saying 94 passengers were on board the Boeing 717 aircraft departing Atlanta on Monday morning “when a haze inside the aircraft was observed.” It said pilots declared an emergency to get priority handling from air traffic controllers.

Once the plane landed, slides were deployed so that passengers could quickly exit. Delta spokesperson Samantha Moore Facteau said by email that “EMTs attended to two customers.”

“Nothing is more important than the safety of our customers and people,” the airline’s statement said, “and we apologize to our customers for the experience.”