Several bystanders were also wounded in the attack.
An Israeli military spokeswoman confirmed an air raid had taken place but did not immediately provide details.
Israel frequently raids Gaza in what its officials say are efforts to stop cross-border rocket fire and other attacks.
Hamas seized control of Gaza in June last year, pushing the rival Fatah faction back into the West Bank.
Signs of torture
Earlier on Tuesady, Hamas denied being involved in the killing of a Fatah security official whose body was discovered south of Gaza City, a day after he was kidnapped from his home.
Marks on the body of Sami Khattab, a former officer in the Palestinian intelligence, suggested he had been tortured, members of his family said.
The wife of the dead officer has accused the internal security forces at the interior ministry in Gaza, of kidnapping and killing her husband.
Hamas has called for an investigation into the killing.