GAZA CITY, Gaza Strip (AP) – A bomb ripped through an elevator shaft at Palestinian intelligence headquarters Saturday, seriously wounding the intelligence chief and nine others in what security officials called an assassination attempt. A bodyguard was killed in the blast.

There was no claim of responsibility. However, the explosion came at a time of growing tensions between the Islamic militant Hamas government and moderate President Mahmoud Abbas over control of the security forces.

The intelligence chief, Tareq Abu Rajab, who survived an assassination attempt two years ago, is an Abbas ally and a top member of Abbas’ Fatah movement. Fatah did not openly accuse Hamas of being behind the blast, but Fatah members demanded that Abbas dissolve the Hamas government and call early elections.

The blast went off before noon Saturday at the heavily guarded four-story intelligence headquarters in northern Gaza City. Abu Rajab and six aides and bodyguards got into an elevator and were close to the second floor when the blast went off. A bodyguard was killed immediately, and Abu Rajab and five others in the elevator were seriously wounded, sustaining injuries to the lower body.

Three others were also hurt, including a secretary riding in an adjacent elevator, doctors said.

The wounded were driven to nearby Shifa Hospital in cars of the intelligence service. Fellow agents fired in the air from the windows of the vehicles to clear the way. Several members of a new Hamas militia fired towards the vehicles, possibly because they believed they were coming under attack, witnesses said.

Abu Rajab underwent surgery at Shifa and was to be taken to an Israeli hospital, doctors said.

The explosion caused massive damage and bomb experts were sent to the scene to investigate.

Khaled Abu Hilal, spokesman for the Hamas-controlled Interior Ministry, suggested the blast was set off when one of Abu Rajab’s bodyguards inadvertently dropped a hand grenade. The claim was dismissed by the intelligence service which said Abu Rajab was the target of an assassination attempt.

Some Fatah members demanded that Abbas dissolve the Hamas government and call new election. A group calling itself the Fatah Protection Unit also demanded that Hamas disband its 3,000-strong militia within three days. The milita was deployed earlier this week, despite Abbas’ vehement opposition.

If the miltia is not removed, “we are ready to deploy our men and our fighters in the streets … to protect Fatah men and all of Palestinian society,” the statement said. Palestinian Prime Minister Ismail Haniyeh of Hamas canceled all appointments for Saturday.

Haniyeh formed a committee to investigate the incident, said government spokesman Ghazi Hamad.

“We are asking not to make early judgments, accusations or responses that might lead to tension in the Palestinian streets,” said Hamad, in apparent anticipation of Hamas being held responsible.

Abu Rajab is a key ally of Abbas, and last week was sent by the Palestinian president to Jordan to look into Jordanian suspicions that Hamas was trying to smuggle explosives into the kingdom and carry out attacks there.

The 2,000-member intelligence service and most members of the security forces are loyal to Abbas. Abu Rajab has also been involved in security coordination with the United States and Israel. He survived an assassination attempt two years ago when gunmen fired on his convoy. At the time, he was seriously wounded and two of his bodyguards were killed.