Two main suspects in the killing of a pro-Palestinian Italian activist died on Tuesday and a third was captured during a raid by Hamas security forces trying to detain the fugitives, the Hamas-run Interior Ministry said.

Hamas said one of the dead militants, a Jordanian, had shot himself after throwing a grenade that had killed the second when the Hamas forces stormed the building where they had been hiding in the central Gaza Strip.

Open gallery view In this Wednesday, Oct. 29, 2008 photo, Palestinian activist Vittorio Arrigoni carries an aid box from the 'Free Gaza' boat in Gaza city. Credit: AP

Three members of the Hamas security forces were also wounded in the battle to capture the al Qaeda-inspired militants who were behind Vittorio Arrigoni's killing last week.

The group had abducted Arrigoni on Thursday and threatened to execute him unless their leader, detained by Hamas last month, was freed. Arrigoni was found strangled on Friday.

Three other members of the group were arrested in the raid, though they were not the main suspects in Arrigoni's death. His killing triggered outrage among Palestinians in Gaza and posed an unprecedented challenge to Hamas.

Hamas security forces had surrounded the building earlier in the day. An attempt to negotiate the surrender of the fugitives had failed.

The militants were jihadist Salafists who espouse a more radical form of political Islam than Hamas and appear to be attracting recruits, including from among Hamas ranks.

Arrigoni, 36, had lived in Gaza since arriving in 2008 aboard a humanitarian aid boat that Israel had admitted despite imposing a blockade on the territory. The security forces are already holding two suspects.

Hundreds of Palestinians took part in a symbolic funeral for Arrigoni on Monday.