Ryanair planes are seen at Dublin Airport, following the outbreak of the coronavirus disease (COVID-19), Dublin, Ireland.Jason Cairnduff | ReutersRyanair said one of its planes was forced into an emergency landing at Thessaloniki airport in Greece shortly after takeoff ​on Friday after a window was "dislodged", with two industry sources saying ​a passenger was partially sucked out of it.The airline said one ⁠person received medical assistance, but did not elaborate on the cause.The plane ​was scheduled to fly from Thessaloniki to Memmingen airport in Germany but returned ​to Thessaloniki "when a passenger window dislodged inflight," Ryanair said in a statement.FlightRadar24 showed a Boeing 737 NG jet en route to Memmingen diverted back to Thessaloniki on Friday morning.The same ​plane had diverted back to Thessaloniki on a flight to Sarajevo on Thursday ​evening, also shortly after takeoff, according to the data and a source, although it is ‌unclear ⁠why.Local media in Greece reported that a piece of engine broke off and smashed a window during the flight on Friday, causing the cabin to decompress and sucking one passenger partially out of the window. Two sources with knowledge ​of the incident ​relayed the same ⁠details to Reuters.Ryanair did not immediately respond to an emailed request for comment on that account of the incident."The aircraft ​landed normally and passengers returned to the terminal," Ryanair ​said in ⁠its statement.Unverified videos posted on social media from the inside of the plane showed a broken window and oxygen masks dangling from the ceiling.A Greek airport source ⁠said ​that the aircraft is still on the ground ​in Thessaloniki and investigators are looking into the incident.