Palestinian sources say a Hamas gunman has died and a senior security official was wounded in an exchange of gunfire in the Gaza Strip Wednesday.

They say the exchange occurred in the town of Khan Younis, where the gunman was shot and killed after he ambushed the vehicle of the local commander, Rifat Kulab of the Palestinian Security force.

Palestinian security officials say the commander was taken to an area hospital with several gun shot wounds in the legs.

Hamas says its activist was first fired upon.

Tensions between Hamas activists and Palestinian security forces have escalated since President Mahmoud Abbas recently called for a referendum on Palestinian statehood that implicitly recognizes Israel. Hamas, which has pledged to destroy Israel, strongly opposes such a vote.

A private research organization named the International Crisis Group issued a report Tuesday, saying the Palestinians are "inching toward civil war."

Some information for this report was provided by  AP and Reuters.