A Southwest Airlines flight from Chicago to Newark had to be diverted to Cleveland Wednesday morning after one of the plane's passenger windows cracked.

The startling incident aboard Flight 957 came a little more than two weeks after a woman was killed aboard Southwest Flight 1380 when an engine blew and shattered a window, partially sucking the passenger through the window and forcing the crew to make an emergency landing at Philadelphia International Airport.

No injuries were reported after Flight 957 landed safely at Cleveland-Hopkins International Airport on Wednesday.

Dallas-based Southwest said the plane — en route from Chicago's Midway Airport to Newark Liberty International Airport — diverted to Cleveland for "a maintenance review" after the outer pane of a multi-layer window cracked.

Photos posted on social media showed a large, jagged crack in a window over a wing.

The cause of the crack is under investigation. Southwest said the plane did not lose pressure, as happened in Flight 1380, and the diversion to Cleveland was classified as an "unscheduled stop" and not an emergency landing.

The timing of the incident could hardly be worse for Southwest, the nation's fourth-biggest airline and the No. 2 operator at Philadelphia International Airport. Last week, Southwest executives said ticket sales had slowed since the deadly April 17 engine failure aboard Flight 1380.

>> READ MORE: Terror in the sky: the emergency landing of Southwest Flight 1380

>> READ MORE: After Southwest incident, should child safety seats be required on airplanes?

Bank executive Jennifer Riordan, 43, of Albuquerque, was killed when she was nearly sucked out of the plane. They estimated the sales drop cost the airline between $50 million and $100 million.

After the Philadelphia emergency landing, the Federal Aviation Administration ordered inspections of more jet engines like the one that blew apart at 32,000 feet on that Boeing 737 jet. The National Transportation Safety Board has said it believes one of the blades snapped on the Southwest flight, hurling debris that broke a window.

>> READ MORE: Southwest Airlines sends Flight 1380 passengers $5,000 checks, $1,000 flight vouchers

The Cleveland landing also came a day after the crew of Southwest Flight 1380 was honored at the White House for its handling of the emergency.

All of Southwest's jets are variants of the Boeing 737.

This article contains material from the Associated Press.  This is a developing story. Check back for updates.