The motives for the shootings was unknown, and there was no immediate claim of responsibility. Gunmen from Hamas and Fatah have clashed in recent weeks in a power struggle for control of the Palestinian government following Hamas' victory in January parliamentary elections.
In Gaza City, Mohammed Tatar, 25, was walking down the street when he was shot twice in the head by unknown assailants. He was evacuated to the hospital where he died of his wounds, hospital officials said.
Earlier in Khan Younis, in the southern Gaza Strip, Mohammed Musaabah, 28, another man affiliated with Hamas, was shot in the stomach and leg by an unknown assailant. He was evacuated to the hospital and was undergoing surgery.
There was no word on his condition.
Earlier Tuesday, Palestinian gunmen stormed the headquarters of mobile company Jawwal in Gaza in protest at having their phones cut off in a sign of growing lawlessness in the coastal strip, employees said.
They said around 20 gunmen entered the building saying their cellphone memory cards were not working. A short while later they began shooting, damaging over 10 computers but causing no casualties.
Jawwal, is the mobile subsidiary of Palestinian telecoms firm PalTel "PTEL.AD", which operates in the West Bank and Gaza Strip.
Israeli forces and settlers pulled out of Gaza last year and internal clashes in the territory have raised fears among Palestinians of civil war.
Internal violence in Gaza has been fuelled by a power struggle between Palestinian President Mahmoud Abbas and Hamas Prime Minister Ismail Haniyeh over control of security forces.