The scene of the crash in Israel's Negev desert
A bus carrying Russian visitors has plunged into a ravine in southern Israel, killing at least 24 people, rescue workers say.
More than 50 passengers were on the bus when it came off a desert road and rolled down a steep slope near the Red Sea resort of Eilat.
Several of those hurt were said to be in a serious condition.
The group had only just arrived and were being transported to Eilat from Ovda airport in the Negev desert.
The group had come from the Russian city of St Petersburg. Local media reports said they were travel agents from the city on a trip to survey the Red Sea resort.
Dozens of rescue workers, ambulances and several air force helicopters rushed to the site to evacuate the injured.
Television footage showed the blue bus on its side at the bottom of the ravine.
Several of the passengers were thrown from the bus as it rolled down the slope, an eyewitness said. Luggage and wreckage lay strewn across the slope.
"The injuries are severe," said an unnamed rescue worker at the scene.
"The crash is grave, seriously grave, one of the worst I've seen in all my years in this profession."
Some of the casualties were taken to hospital in Eilat, where medical personnel attending a conference were drafted in to help out. Others were flown to the town of Beersheba, a police spokesman said.
The bodies of the deceased were being flown to Tel Aviv for identification.
Six injured people who were trapped in the bus were freed, an Israeli military officer said.
"They were saved because they were trapped in their seats," the Associated Press news agency quoted the unidentified officer as saying.
In a statement, Israeli Prime Minister Ehud Olmert expressed shock at the "horrific accident".
The road where the accident happened links Eilat, a popular holiday destination, with Ovda airport, some 50km (30 miles) away.
The bus broke through a rail and rolled down a ravine, witnesses said.
It crosses mountainous terrain and involves a series of hair-pin bends.
The driver of another bus said that the vehicle overtook him in a no-passing zone and then crashed through a guard rail, the Associated Press news agency reported.
A taxi driver who saw the accident gave a similar account to Israeli public radio.
"The driver of the bus tried to overtake another bus in a hair-pin curve and lost control of his vehicle," he said.
Traffic police commissioner Meir Or said the driver had survived the crash but was injured, AFP news agency reported.
Mr Or said the driver was being interrogated and that police were trying to determine the speed at which the vehicle had been travelling.
Russian President Dmitry Medvedev sent condolences to relatives of the victims, Russian media reported.
A spokeswoman for Russia's emergencies ministry said two planes were being sent to Israel, one carrying relatives of those involved in the crash and a cargo plane carrying emergency personnel.