Did Belarus 'hijack' a civilian airliner to detain an activist?

Ryanair flight 4978 was about to begin its descent to Vilnius in Lithuania on Sunday when it suddenly changed direction after a "security alert," turning sharply east and descending towards the capital of Belarus, Minsk.

source https://www.cnn.com/2021/05/23/europe/belarus-ryanair-pratasevich-intl/index.html