What does 2 Kings 10:7 mean?

When Jehu’s letter showed up, the city leaders took all seventy of Ahab’s sons, killed them, put their heads in baskets, and sent them to Jehu in Jezreel. 2 Kings 10:7 - Modern Text Bible

(The officials, fearing Jehu’s threat, brutally executed all of Ahab’s male heirs and sent proof to Jehu, showing their loyalty and fear.)