US spy agencies assess that Hamas and another Palestinian group fighting Israel used Gaza’s Al Shifa Hospital to command forces and hold some hostages but largely evacuated the complex days before Israeli troops entered it, a US official said citing declassified US intelligence.

The complex was used by Palestinian groups to command forces fighting against Israel, the US official said, speaking on condition of anonymity.

According to Reuters, US intelligence agencies have not disclosed the evidence on which they based their assessment. The official said the US had independently confirmed the information.

Israel has also alleged that Al Shifa, which it had occupied earlier in the war in Gaza, had been used by Hamas. Israeli troops entered the hospital in November. The targeting of the hospital had stoked global alarm over the fate of civilians and patients who were inside.

US intelligence agencies obtained information that Hamas fighters had largely evacuated the complex days before Israel’s operation and destroyed documents and electronics as they left, according to the American official.

The US intelligence assessment was reported first by the New York Times. A classified version of the assessment was sent to lawmakers in the U.S. Congress.