Israel has claimed responsibility for an attack outside Al-Shifa Hospital in Gaza City that witnesses say killed and wounded dozens of people.
Videos from the scene show multiple people bloodied and strewn across the ground near an ambulance.
Fifteen people were killed and 50 others wounded, Hamas-run health authorities say.
In a statement, Israel said it targeted the ambulance because it was being used by Hamas.
“An IDF aircraft struck an ambulance that was identified by forces as being used by a Hamas terrorist cell in close proximity to their position in the battle zone,” it said in a statement. “A number of Hamas terrorist operatives were killed in the strike. We have information which demonstrates that Hamas' method of operation is to transfer terror operatives and weapons in ambulances.”
A spokesperson for the Palestinian Ministry of Health in Gaza said earlier Friday that the ambulance was in a medical convoy from the hospital, traveling to the Rafah border crossing, and had informed the International Committee of the Red Cross about the move.
The ICRC confirmed it was aware of the scheduled movement of a convoy of vehicles carrying wounded patients from northern Gaza to the south, but it was not part of it, the organization said on Friday.
"We were informed by the MoH (Ministry of Health) about the planned convoy, but we were not part of it," the ICRC said in a statement to CNN.
Earlier Friday the organization said it had received a request from the Gaza Ministry of Health to accompany the convoy.
"Even if we were not present, this is still medical convoy, and any violence towards medical personnel is unacceptable," the ICRC said. "No doctors, nurses, or any medical professionals should ever die while working to save lives."
"Any involvement of the ICRC in evacuating civilians from an area requires the agreement of the sides on the exact terms and conditions so that this can be done safely, and then with the full consent of those evacuated,” the organization said in a previous statement.
This post has been updated with the latest statement from the International Committee of the Red Cross.