An American Airlines pilot died during a red-eye flight from Phoenix to Boston early Monday, the airline said.

"Unfortunately our pilot passed away. We are incredibly saddened by this event and we are focused on caring for our pilot's family and colleagues," an airline spokesperson said.

The flight, which carried 147 passengers and five crew members, was diverted to Syracuse, New York. The airline said the co-pilot landed the jet safely at 7 a.m. ET Monday.

"We landed and had no idea what was going on," said passenger Louise Anderson. "Airport security was waiting for us. They let us know that they were going to get another crew to fly us to Boston."

It wasn't until the second flight with a new crew that passengers were told the pilot had passed away, so "there was no time to panic when we were on the flight," Anderson said. She added that American Airlines "handled the situation really professionally."

the pilot died on our redeye back to Boston (leading to 4h in Syracuse). life is short. do what you love before it's too late. — lulusaurus-rex (@lulakilla) October 5, 2015

Anderson, who was flying home to Boston after competing in a race in California over the weekend, said she slept during most of the trip but remembers the pilot's voice filling the cabin at the start of the flight. "As he was announcing the weather for Boston he said it was going to be 79 or 80 degrees," she said. "He had to correct himself."

The pilot's name and age were not released. The airline did not specify a cause of death.