The Associated Press

WASHINGTON - President Bush sadly informed the nation Saturday of the worst space tragedy in 17 years, saying "The Columbia is lost. There are no survivors."

He consoled the families of the astronauts in a telephone call. Then in an address from the White House Cabinet Room he said of the seven-member crew, "We can pray they are safely home."

Bush said the loss of the space shuttle and its astronauts "brought terrible news and great sadness to our country," but he pledged to make sure their lives' mission continued.

"Our journey into space will go on," he said.

"Millions of Americans are praying for you," Bush told the families. They were gathered in Florida, where they had expected to welcome their loved ones home from space.

Bush also telephoned Mexican President Vicente Fox, Israeli Prime Minister Ariel Sharon, French President Jacques Chirac and Russian President Vladimir Putin before the address. He telephoned Canadian Prime Minister Jean Chretien afterward.

Israel's first astronaut, Ilan Ramon, was aboard the shuttle. Bush and Putin discussed how the tragedy would affect plans for a shuttle to bring provisions to the space station manned by both Russian and Americans.

The accident occurred as Bush was readying the nation for potential war with Iraq. He received word of the shuttle's loss shortly after a national security briefing at Camp David, where he had planned a restful weekend away from Washington.

The call came from NASA Administrator Sean O'Keefe.

Addressing the nation later, Bush said of the crew members, "These men and women assumed great risk in the service to all humanity. The astronauts knew the dangers and they faced them willingly."

Flanked by two flags, Bush spoke slowly, his voice falling almost to a whisper at some points, his brows furrowed and his mouth downturned.

Quoting Scripture, the president said, "The same creator who names the stars also knows the names of the seven souls we mourn today. The crew of the shuttle Columbia did not return safely to earth but we can pray they are safely home." His eyes were glistening as he concluded.

Bush read the names of the seven astronauts - six Americans and the Israeli.

"All Americans today are thinking as well of the families of these men and women who have been given this sudden shock and grief. You are not alone. Our entire nation grieves with you and those you love will always have the respect and gratitude of this country.

"The cause in which they died will continue," Bush said. "Mankind is led into the darkness beyond our world by the inspiration of discovery and the longing to understand. Our journey into space will go on."

Earlier, NASA Administrator O'Keefe, announcing the shuttle's demise, said he had spoken with Bush and the president had offered his "full and immediate support" to determine what had gone wrong and what to do next. O'Keefe spoke at a news conference in Cape Canaveral, Fla.

Homeland Security Secretary Tom Ridge coordinated the government response. He contacted officials in five states, including Texas, where debris from the shuttle fell.

Under an executive order signed recently by Bush, Ridge is the coordinator of all domestic incidents of this magnitude, even when terrorism is not suspected.

Ridge, working from the White House, contacted O'Keefe, Mike Brown of the Federal Emergency Management Agency, and officials at the military's Northern Command., which was created after the Sept. 11, 2001, terrorist attacks solely to defend U.S. territory. Ridge decided that FEMA, which becomes part of his department March 1, would be the lead agency for response and recovery.

FBI spokeswoman Angela Bell said there was no indication of terrorism.

Vice President Dick Cheney was briefed Saturday morning in Texas, where he was spending the weekend hunting, said spokeswoman Jennifer Millerwise. She said he was not in the part of Texas where the shuttle was lost.

The loss of the Columbia was the worst space tragedy since the shuttle Challenger disintegrated in the sky 73 seconds after takeoff from the Kennedy Space Center on Jan. 28, 1986, killing all seven crew members.