Israel struck an ambulance in Gaza City on Friday that it said was carrying militants, but which health authorities in the Hamas-controlled enclave said was evacuating wounded people from the besieged north to the south of the territory.

Ashraf al-Qidra, spokesperson for the health ministry in Gaza, said the ambulance was part of a convoy that Israel targeted leaving al-Shifa Hospital, adding that “a big number” were killed and wounded but without giving figures.

Qidra said Israel had targeted the convoy of ambulances in more than one location, including at al-Shifa Hospital gate and at Ansar Square a kilometre away.

Israel’s military said it had identified and hit an ambulance “being used by a Hamas terrorist cell” in the battle zone.

It said a number of Hamas fighters had been killed in the strike and accused the group of transferring both militants and weapons in ambulances.

It gave no evidence to support its assertion that the ambulance was linked to Hamas but said in a statement it intended to release additional information.

World Health Organisation Director-General Tedros Adhanom Ghebreyesus said in a social media post he was “utterly shocked by reports of attacks on ambulances evacuating patients”, adding that patients, health workers and medical facilities must be protected.

Earlier on Friday, Qidra said ambulances would send critically injured Palestinians who urgently need to be taken to Egypt to be treated from besieged Gaza City to the south of the enclave.

Israel, which has accused Hamas of concealing command centres and tunnel entrances in al-Shifa hospital, ordered all civilians to leave the north of Gaza last month and its military encircled the area on Thursday.

Despite its order for civilians to leave northern areas of Gaza, Israel’s military has continued to bombard the south of the strip as well.

Hamas and al-Shifa hospital authorities have denied the facility is used as a base by militant fighters.

Video shared on social media, which Reuters has verified, showed people lying in blood next to an ambulance with flashing lights on a city street as people rushed to help.

Another video showed three ambulances standing in a line, with about a dozen people lying either motionless or barely moving next to them. Blood was pooled nearby.