Local sources said that Salafist activists, affiliated with the Islamic State (ISIS), are responsible for the vehicle bombings.
The cars belonged to officials of Islamic Jihad, Hamas and its armed wing, the Qassam Brigades.
Several auto explosions took place in Gaza Sunday morning in the Sheikh Radwan neighborhood, security officials from the Gaza strip said.
Security forces and rescue teams rushed to the scene and began to investigate the incident.
The Hamas-run Interior Ministry said an investigation had been launched.
There were no immediate claims of responsibility, but initial suspicions pointed to an Islamic State-affiliated group in the Gaza Strip.
Extremists in Gaza inspired by ISIS have attacked Hamas positions in the past and have also fired rockets at Israel in an attempt to undermine Hamas by violating the cease-fire between Israel and Hamas that followed last year’s war.
A spate of attacks has targeted public buildings, officials, global organizations and others seen as linked to the establishment in Gaza.
Islamic State supporters have threatened to turn the Gaza Strip into another of their Middle East fiefdoms, accusing Hamas, the organisation that rules the Palestinian territory, of being insufficiently stringent about religious enforcement.
Salafi groups have been angered by a Hamas crackdown and claimed in recent weeks that around 100 of their members or supporters were behind bars. Gaza’s border with Egypt also remains strictly controlled.