WARSAW, Poland — Polish ****** say they have detained 21 people in connection with a false **** ****** that caused 800 people to be evacuated and four flights to be diverted from an airport near the capital.

The **** ****** occurred late Sunday and affected Warsaw’s Modlin Airport, which is north of the capital and serves budget airlines.

Dawid Marciniak, a ****** official, said Monday that ****** traced the hoax call to a party attended by 21 people, all of whom he said were *****. Since nobody admitted to making the call, ****** detained them all.

He said whoever is found guilty could face a prison sentence ranging from six months to eight years and will also have to cover the financial costs of the security operation on Sunday.