A Palestinian militant leader claimed Tuesday that his group had seized a Jewish settler in the West Bank in addition to a captured Israeli soldier being held in a "secure place."
The Popular Resistance Committees, a violent group with close ties to the Hamas-led Palestinian government, made the new claims about captive Israelis. The PRC was one of three groups that took part in Sunday's cross-border infiltration from Gaza in which militants killed two Israeli soldiers and abducted Israeli Cpl. Gilad Shalit.
"The soldier is in a secure place that the Zionists cannot reach," PRC spokesman Mohammed Abdel Al said, acknowledging that Shalit was still alive.
No more information regarding the 19-year-old soldier was revealed. Israeli officials have said they believe Shalit was lightly wounded during the raid and that he is being held in southern Gaza.
"We are at the edge of a cliff," Israeli Foreign Ministry spokesman Mark Regev said. "If the Palestinians make the right choices, act responsibly, the crisis can de-escalate."
Abdel Al also said his group had taken a Jewish settler in the West Bank hostage. Israel Radio reported the settler had been hitchhiking Monday night and failed to return home.
"We're looking into reports of a missing person," police spokesman Micky Rosenfeld said.
Abdel Al said the release of more information depends on Israel.
"The Zionists are looking for any information. We remind them there is nothing for free," he said in the Gaza Strip.
Israeli Prime Minister Ehud Olmert has rejected a demand to release Palestinian prisoners in return for information about Shalit. Instead, he approved plans for a large military push into Gaza and threatened to hit Islamic militants and their leaders.
About 3,000 troops, along with tanks and armored vehicles, massed along Israel's border with Gaza. Commanders said they were prepared and awaiting orders to move in.
"We will not hold back on our efforts, and to our great sorrow, part of this price will be paid by the residents of the Gaza Strip," Haim Ramon, a senior Israeli Cabinet Minister, told Army Radio.
"This strike will come and it will be very painful. In order to stop this, I call on authorities in the Palestinian Authority to do all they can to bring Gilad home."
Secretary of State Condoleezza Rice urged Israel to "give diplomacy a chance."
"There really needs to be an effort now to try and calm the situation," Rice said en route to Pakistan.
Although Israel frequently carries out air raids in Gaza, ground troops have entered the area only three times since Israel withdrew from there in September.
An explosion in Gaza Tuesday that killed one and injured two appeared not to have been caused by an Israeli airstrike as witnesses claimed.
The Israeli Defense Forces denied any involvement and a review of footage of the aftermath suggested the blast was not caused by a missile. Sources in Gaza told FOX News the incident appeared to be a "work accident" — a term used when explosives are accidentally set off by their handlers.
Israel clamped a tight closure on Gaza that prevented merchants from leaving the area and fishermen from sailing off the Mediterranean coast, the army said. It closed all crossings into Gaza.
Hundreds of Palestinians were stranded on the Egyptian side of the border at the Palestinian-controlled Rafah crossing, said the director of security at the Palestinian crossings, Salim Abu Safiah.
Anticipating an invasion, Palestinian militants piled up sand on roads near the border and in Gaza City.
"We are ready to confront any stupid act that the Zionists might commit," said Abu Obeida, spokesman for Hamas' military wing.
The group also claimed that militants from various factions had taken up positions throughout northern Gaza.
The moderate Palestinian president, Mahmoud Abbas, met with leaders of the Hamas-led government Monday night and urged them to secure Shalit's release. Abbas also has been working closely with Egyptian mediators, who hold influence over Hamas.
Egyptian officials said the government asked Hamas to release the soldier and has deployed 2,500 extra troops along the border with Gaza to prevent an influx of Palestinians if Israel invades. Egypt also imposed a nighttime curfew along the border.
Intelligence chief Omar Suleiman has urged Hamas leader Khaled Meshaal, who is in Syria, to push for Shalit's release, the officials said on condition of anonymity because of the sensitivity of the situation.
Participants said Abbas told the Hamas leaders they would be responsible for any Israeli reprisals. Prime Minister Ismail Haniyeh said he did not have any information about the soldier, the participants said.
The abduction has exposed divisions within Hamas, which maintains separate political and military wings. While the military wing claimed responsibility for Sunday's attack, local political leaders have said Shalit should be freed.
Ghazi Hamad, a government spokesman, said he feels sorry for the soldier and wants him protected.
"We ... don't want to reach a situation of bloodshed, here or there," he told Army Radio in Hebrew.
Mohammad Nazal, a Damascus-based member of the Hamas politburo, said the militant group won't agree to release the Israeli soldier "without something in return."
"This is the popular demand and we cannot let down our people," he told The Associated Press in a telephone call.
The militants holding Shalit issued their first demands Monday, saying Israel should release all jailed Palestinian women and children under 18 in return for information about Shalit. Officials estimate there are 500 such prisoners.
The issue of the estimated 8,000 prisoners held by Israel is extremely sensitive in Palestinian society. Ordinary Palestinians have expressed overwhelming support for the kidnappers, saying the soldier should not be freed without the prisoners' release.
The Associated Press contributed to this report.