Gaza's civil defence agency said Israeli air strikes and gunfire killed 23 people in the war-ravaged Palestinian territory on Sunday, including at least three children.

Civil defence spokesman Mahmud Bassal told AFP that his services "transported 23 martyrs, including several children and women" killed in various locations around the Gaza Strip.

Bassal said two children were killed in an air strike on their home in Gaza City's Zeitun neighbourhood in the early morning, adding "the house was completely destroyed".

A family member, Abdel Rahman Azzam, 45, told AFP he was at home when he "heard a huge explosion at my relative's house".

"I rushed out in panic and saw the house destroyed and on fire," he added.

"We evacuated more than 20 injured people, including two martyrs -- two children from the family. The screams of children and women were non-stop," Azzam said.

"They bombed the house with a missile without any prior warning. This is a horrific crime. We sleep without knowing if we will wake up."

Elsewhere, Bassal said a drone strike on a tent housing displaced people near the southern city of Khan Yunis killed five people including a child.

He said that other casualties included a young man killed "by Israeli fire this morning while waiting for aid" near a humanitarian distribution centre in the southern city of Rafah.

The Israeli military issued an evacuation order on Sunday for parts of Gaza City and nearby areas in the territory's north, warning of imminent action there.

The civil defence agency later said an Israeli air strike hit a house in Gaza City, killing three people.

Israel'smilitary campaign has killed at least 56,412 people in Gaza, also mostly civilians, according to Hamas-run territory's health ministry. The United Nations considers these figures to be reliable.