One of the four bodies handed over from Gaza to Israel on Thursday does not include a hostage, the Israel Defense Forces said, calling it a “very serious violation” by Hamas.

The fourth body was not Shiri Bibas—nor was it a match for another hostage, the IDF said.

This from abcnews.go.com.

Thursday marked the latest return of deceased hostages as part of the group’s ceasefire deal with Israel.

Israel and Hamas had confirmed the names of the four bodies returned to Israel Thursday as Oded Lifshitz, a journalist and peace activist, and Shiri Bibas and her two children—Ariel and Kfir Bibas.

After Israeli officials conducted forensic analysis to confirm the identities of the bodies, the IDF said the bodies of Lifshitz and Shiri Bibas’ two children were identified. But the fourth body cannot be identified as an abductee.

The IDF said in a statement:

It is an anonymous body without identification.

This is a very serious violation by the Hamas terrorist organization, which is required by the agreement to return four dead abductees.

We demand that Hamas return Shiri home along with all of our abductees.

The statement added:

We share the deep sorrow of the Bibas family at this difficult time.