Palestinian militants accidentally set off a large blast at a Hamas training base in the central Gaza Strip on Thursday, killing two members of the violent Islamic group and wounding another, a Palestinian medical official said. Hamas initially blamed Israel for the blast, but later acknowledged that it was caused by a mishandling of explosives, saying its men died while performing a "holy mission." The Israeli military denied involvement. Hamas security men kept photographers and TV cameramen away from the scene. Dr. Moaiya Hassanain, a Palestinian Health Ministry official, confirmed the deaths.

The incident happened amid new signs that Israel is moving closer to a cease-fire with Hamas militants in the Gaza Strip. Israeli defense officials said Amos Gilad, a senior Defense Ministry official, traveled to Cairo on Tuesday for talks with Egyptian mediators. The officials spoke on condition of anonymity due to the sensitive nature of the talks.

Also Thursday, Hassanain said Israeli troops killed a 60-year-old Palestinian farmer near the Gaza-Israel border. The Israeli military had no comment. But Israel often shoots at Palestinians near the border, where militants frequently attempt to plant explosives or sneak into Israel.

Israel has been battling Hamas since the Islamic group violently seized control of Gaza last June. In addition to its military activity, Israel has imposed a tough economic blockade on the strip.

But violence in the Gaza Strip and southern Israel has eased overall in recent weeks as Egypt, with U.S. backing, pressed Hamas to stop its rocket fire into Israel and urged Israel to halt military strikes.

The truce efforts intensified after a fierce round of fighting that began in late February and killed more than 120 Palestinians, including dozens of civilians, as well as three Israelis.

As part of the truce talks, Hamas wants Israel to reopen Gaza's border crossings. Hamas also wants to have some sort of presence at the crossings. Israeli defense officials have not ruled that out, as long as Israel is allowed to monitor the passages as well.

Hamas spokesman Ayman Taha confirmed Wednesday the talks were under way with Egyptian mediators.

"As we have always said, the ball is in Israel's court," Taha said. "We cannot forget that.... Every single minute they are committing new aggressions against the Palestinians."

In Washington, meanwhile, the State Department again ruled out U.S. talks with Hamas, which it designates as a terrorist organization.

"It'll be a cold day in hell before you see a change in U.S. policy with respect to discussing, winking at, nudging, looking at or otherwise dealing with a terrorist organization," deputy spokesman Tom Casey said.

Israel also received a boost of support from Sen. John McCain (web|news|bio), who said that he understands Israel's tough response to Palestinian rocket fire and said there is no point in negotiating with Hamas.

"It is very difficult to negotiate with an organization that is dedicated to your extermination," the likely Republican presidential nominee said during a visit to Israel.

Israel on Wednesday barred Palestinians from the West Bank and Gaza Strip from entering the country over a coming Jewish holiday, fearing Hezbollah guerrillas may try to carry out a major attack.

The Purim holiday, which starts at sundown Thursday, coincides with the end of a 40-day Muslim mourning period for Hezbollah commander Imad Mughniyeh, who was killed in a car bombing in Syria last month. Israel has denied involvement, but the Lebanese guerrilla group has blamed Israel and vowed revenge.

The Israeli army said the closure would remain in effect through Sunday night, preventing thousands of Palestinian workers and merchants from entering Israel.

Most come from the West Bank, but small numbers of merchants from the Gaza Strip are allowed in. Palestinians needing treatment at Israeli hospitals will be able to enter, and cargo crossings will keep operating, a military spokesman said on condition of anonymity, citing policy.