MOSCOW - An explosion tore through the upper floors of a Moscow apartment building before dawn Sunday, Russia news agencies reported. Authorities said it may have been caused by a gas leak.
The blast hit about 4 a.m., destroying several apartments in the buildings and causing an unknown number of casualties, the reports said.
The explosion struck a 12-story building on Chertanovsky Street, a thoroughfare on the southern edge of the city.
The cause of the blast was not immediately determined, although authorities said initial indications were that it was caused by gas.
Natural gas explosions in Russia's often-shabby apartment buildings are not uncommon, but fears about terrorism are running high in the wake of a series of explosions that authorities blame on Chechen separatist rebels, including a bombing last month on the Moscow subway that killed 41 people.
Some 300 people died in apartment explosions in September 1999 that officials blamed on the rebels.
By IBRAHIM BARZAK, Associated Press Writer
EREZ CROSSING, Gaza Strip - Palestinian gunmen and suicide car bombers staged an elaborate attack against a major Israeli checkpoint on Saturday, in what militant groups called revenge for recent airstrikes targeting their members.
Four assailants and two Palestinian policemen were killed, but no Israeli soldiers were hurt.
The attackers used vehicles that looked nearly identical to Israeli army jeeps, complete with military markings, black-and-white army license plates and flashing lights on the roof. It was the latest surge of violence ahead of a proposed Israeli withdrawal from the Gaza Strip.
Militants said Saturday they were stepping up attacks to show they were forcing Israel out of Gaza. Israel was expected to intensify military strikes ahead of a withdrawal to avoid the impression of surrender. Seven Palestinians have been killed in targeted Israeli air strikes in Gaza City in the past week.
The attack began at about 10 a.m. when a Palestinian taxi sped into the Erez crossing zone between Gaza and Israel and exploded just outside a heavily fortified army checkpoint.
Moments later, two more attackers in a jeep with Israeli military markings pulled up. One of the men jumped out and opened fire with an assault rifle. Troops fired back, killing the pair.
A second vehicle disguised as an army jeep blew up outside the crossing zone, apparently after Palestinian policemen guarding the Gaza side blocked its path. Two Palestinian policemen were killed.
The military said they were hit by the spray of shrapnel as the third car exploded, but Palestinian hospital officials said the two had gunshot wounds. Nineteen people, including police officers and taxi drivers, were wounded, two of them critically.
The three main Palestinian militant groups — Hamas, Islamic Jihad and Al Aqsa Martyrs' Brigades — said they were behind the attack, calling it a joint "self-sacrifice operation."
The attacks followed promises of revenge for recent the air strikes.
Body parts were strewn around the wreckage of two vehicles from the attack. One of the jeep's engines sat in the road, and a dog lay dead in a thick pool of blood.
"The sound of the explosion was huge and powerful, followed by intense machine gun fire from the Israeli army outpost," taxi driver Ali al-Basyouni, 38, said.
Israeli Prime Minister Ariel Sharon (news - web sites) has said he would withdraw from much of the Gaza Strip if peace talks with the Palestinians remain frozen in coming months. Sharon says the "disengagement" is meant to reduce friction with the Palestinians during an interim period, until talks on a final peace deal can resume.
The Palestinians suspect Sharon is trying to avoid negotiations during which he presumably would have to give up more land than in a unilateral withdrawal. They fear Israeli-imposed boundaries could become permanent.
Israel will hold off on a withdrawal from Gaza until after the November presidential election in the United States, security officials said this week.
Israeli government spokesman Avi Pazner said the air force would keep sending helicopters and warplanes to launch airstrikes against militants at every chance.
At Saturday's funeral for the two Palestinian policemen killed earlier in the day, a member of Al Aqsa told a crowd that militants would continue attacks until Sharon pulls soldiers out of Gaza.
"He (Sharon) is not leaving Gaza because he is feels like it; he is being forced to leave Gaza," the man said.
Hanni al-Masri, a reporter at the Palestinian daily Al-Ayyam, said the Palestinian militants want any withdrawal to look like they pushed the Israelis out.
The Erez crossing has been attacked several times during more than three years of fighting. Past attacks have temporarily shut down the crossing zone's large industrial park, where 6,000 Palestinians work in factories.
Also Saturday, Israeli soldiers shot and killed a 19-year-old Palestinian policeman in a West Bank refugee camp.
Israeli forces on a routine patrol in the Tulkarem refugee camp opened fire after the man aimed an assault rifle at them during a clash between soldiers and dozens of stone-throwing youths, an army spokeswoman said.
Israel bars Palestinian security forces in the West Bank from carrying weapons and has told Palestinian commanders that any officers spotted on the streets with weapons could be considered hostile combatants, the spokeswoman said.