Hamas officials say the body of an Italian pro-Palestinian activist kidnapped a few hours earlier has been found.
The officials said Hamas police stormed an apartment in Gaza City belonging to a member of the extremist group that released a video of the activist. After a clash early Friday, Hamas police found the body, they said. It was not clear how he died.
The International Solidarity Movement had identified the kidnapped activist as Vittorio Arrigoni, 36, from Italy. In the video, the group demanded that Hamas release its leader and two other members arrested last month.
The officials spoke on condition of anonymity because no announcement was made.
Gaza police were surrounding the small house where the clash took place. A police officer said the body was inside. He said four people were arrested in another location in connection with the abduction.
This was the first kidnapping of a foreigner since Hamas overran the Gaza Strip in 2007.
The video released Thursday showed a man with a thick black blindfold and a large bruise on his face. Apparently seated, he was held in front of the camera by an unseen person.
In a message on the video, the extremist group that calls itself Monotheism and Holy War demanded that Hamas free its leader, arrested in early March, and two other members whose names had not been previously known.
Sheikh Abu Walid-al-Maqdasi, the leader of the group, was arrested in a crowded beachside neighborhood of Gaza City last month.
Early Friday, the group posted a statement on its website denying responsibility for the abduction.
Arrigoni had not been heard from in the past 24 hours, said ISM co-founder Huweida Arraf.
In the past, all foreign kidnap victims in Gaza had been released unharmed.
Before the body was found, the Italian Foreign Ministry said in a statement that it was aware of the kidnapping, was in touch with Arrigoni's family and was taking steps to ensure his safety. "Foreign Minister Franco Frattini is in touch with diplomats in the country and is following the situation with great attention," the statement said.
Hamas itself is a fundamentalist Islamic group, but it faces challenges from even more extremist offshoots of Islam, including Walid-al-Maqdasi's group, that take inspiration from al-Qaida and the world jihad movement. Hamas has denied that al-Qaida has a presence in Gaza.
Kidnappings of foreigners were common before the Hamas takeover. Most of those abducted were foreign correspondents, including Alan Johnston of the BBC, who was abducted and held for 114 days before being freed in July 2007, just after Hamas overran Gaza, expelling forces loyal to Palestinian President Mahmoud Abbas.
ISM operates in the West Bank and Gaza and is known for trying to prevent the Israeli military from carrying out its missions. Arraf said this activist has been going in and out of Gaza for more than two years. He was working with farmers and fishermen.
The ISM incident that got the most attention was the 2003 death of American activist Rachel Corrie, who was crushed by an Israeli military bulldozer in southern Gaza while trying to block its path.