Four flights in Europe were targeted by bomb threats on Tuesday.

They included two flying to Poland, one landing in Spain, and another in Bulgaria. One of them was diverted, while the other airplanes reached their destinations before being checked for explosives.

Here's what we know:

Flight impacted: Scandinavian Airlines Flight 751 out of Copenhagen

Scandinavian Airlines Flight 751 left Copenhagen around 8:30 a.m. for Warsaw on Tuesday. It landed as expected an hour later without diversion. An airline spokesperson confirmed that a threat had been made against the flight.

"The matter is now being handled by the police in Warsaw," they said in a statement.

Flight impacted: LOT Polish Airlines Flight 286 out of London Heathrow

Thirty minutes after that flight landed, a LOT Polish Airlines plane diverted to Warsaw-Modlin Airport — about 25 miles from its intended destination of Warsaw-Chopin Airport.

In a statement, the airline said it "was notified by airport authorities of a potential security threat" on board Flight 286 from London Heathrow.

It added that the aircraft taxied to a designated parking stand and no suspicious items were found in a security inspection. Passengers were then taken to Chopin Airport by coach.

Modlin Airport was closed for around two hours before the threat was cleared.

Flight impacted: Ryanair Flight 4116 out of Manchester, England

A Ryanair flight from Manchester, England, to Murcia, Spain was also targeted on Tuesday.

The Spanish government's representative for the region, Francisco Lucas, said on X that security protocols were activated due to a bomb threat on the flight.

An hour and a half later, Lucas said the Civil Guard had ruled out the presence of explosives and the airport resumed normal activity. Ryanair did not immediately respond to a request for comment from Business Insider.

Flight impacted: Flight at Sofia Airport

Bulgaria's national broadcaster, BNT, then reported that a plane that had landed at Sofia Airport was being checked for explosives, citing Lyubomir Nikolov, the acting secretary-general of the Interior Ministry.

The incidents followed a bomb threat on Monday. In that incident, a Wizz Air flight from London Luton to Sofia "was diverted to Budapest following a bomb threat received during the flight," an airline spokesperson said.

This is a developing story.