SOUTH BURLINGTON, Vt. — United Airlines says the windshield on a flight from Vermont to Washington, D.C., cracked because of a maintenance issue, not a bird strike as was initially reported.

The incident happened Thursday when the windshield on United Airlines Flight 4331 cracked shortly after takeoff. Burlington International Airport officials tell WPTZ-TV that the plane landed safely and nobody was hurt. The 50 passengers took another flight to Washington.

The aircraft’s windshield was heavily damaged. An investigation is ongoing.