No one was injured in the incident, which came two weeks after an engine on a Southwest 737 ripped apart in flight and shattered a window, killing a female passenger in the first U.S. airline passenger fatality since 2009.

The cause of Wednesday’s crack in one of the window’s multiple panes was not immediately known.

The flight, Southwest 957, was traveling to Newark Liberty International Airport from Chicago Midway International Airport with 76 passengers on board. The crew diverted the Boeing Co (BA.N) 737-700 to Cleveland-Hopkins International Airport at about 11 a.m. EDT to inspect a layer of a windowpane, said Southwest spokesman Brian Parrish.

“The aircraft has been taken out of service for maintenance review,” Parrish said.

FAA spokesman Tony Molinaro, who confirmed no one was hurt, said the organization was investigating the incident.