A plane made an emergency landing at Tucson International Airport Sunday morning, after smoke filled the cockpit and cabin, according to authorities. Tucson Airport spokesperson Jessie Butler said United flight 6517 took off from Tucson to Los Angeles at 6 a.m. with 77 passengers on board. While in the air, the plane filled with smoke, causing the pilot to turn around back to Tucson for an emergency landing, said Butler. "Everybody was screaming, totally terrified," said Jessica Scott, who was on the plane. Butler said the smoke was coming from the cockpit. There was no fire, but passengers said the smoke made it hard to breathe. "I was too concerned with my daughter that I had put a blanket over her head because for a newborn the smell was just too strong," said Tiffany Lizares, who had her three-month-old daughter with her on the flight. The plane was evacuated on the runway and the aircraft was then taxied to the gate, said Butler. Passengers described a hectic evacuation. "We were so scared that I actually at the door handed my baby to my husband and told him to run because he's a faster runner than I am," said Lizares. Her husband, Rylan Lizares, said, "Luckily I ran out to the left, which had a exit ramp. The other passengers who went to the right or over the wings had to jump out of the plane, so it was about a six foot drop." Authorities are investigating the cause of the smoke.