UNITED NATIONS -- UN Secretary-General Antonio Guterres on Thursday condemned the killing of more than 100 Palestinians waiting for aid in northern Gaza, said his spokesman.

"The secretary-general condemns the incident today in northern Gaza in which more than 100 people were reportedly killed or injured while seeking life-saving aid. The desperate civilians in Gaza need urgent help, including those in the besieged north where the United Nations has not been able to deliver aid in more than a week," said Stephane Dujarric, the spokesman, in a statement.

Palestinian officials said Israeli forces on Thursday opened fire on a crowd of Palestinians waiting for aid on a coastal road west of Gaza City, killing 104 people and wounding more than 760 others.

An Israeli military spokesman said the troops fired "in self-defense" after Gazans attacked and looted aid trucks that entered the Gaza Strip early in the morning.

Dujarric said there was no UN presence at the site of the tragedy. He said the incident needs to be investigated and there will be time for accountability.

Guterres reiterates his call for an immediate humanitarian cease-fire and the unconditional release of all hostages. The secretary-general once again calls for urgent steps so that critical humanitarian aid can get into and across Gaza to all those in need, said the spokesman.

Guterres is appalled by the tragic human toll of the conflict in Gaza, in which more than 30,000 people have now reportedly been killed and over 70,000 injured. Tragically, an unknown number of people lie under the rubble, said Dujarric.