A shrapnel-filled bomb believed strapped to a homicide attacker ripped apart a commuter train Friday near Chechnya (search), killing 42 people and wounding nearly 200 in what Russia's president called an attempt to disrupt weekend parliamentary elections.

The blast near this city in southern Russia was the latest in a series of homicide bombings and other attacks that have foiled security measures and killed more than 275 people in and around the rebellious region of Chechnya and in Moscow (search) in the past year.

The remains of the suspected bomber were found with grenades still attached to his legs, Federal Security Service chief Nikolai Patrushev (search) said. Three women also were involved in the attack -- two who jumped from the train just before the blast, and one who was gravely injured and unlikely to survive, he said.

Authorities suspect other accomplices may have been watching from cars near the site of the blast, which threw passengers from the train and sent its second car crashing onto its side, trapping victims beneath the buckled wreckage.

The explosion tore through the train around 8 a.m., a rush-hour attack that seemed calculated to kill and injure as many people as possible. The train was about 500 yards from the station at Yessentuki (search), 750 miles south of Moscow, and officials said many passengers were students from local schools and universities.

Thirty-five people died at the scene of the blast and seven others in hospitals, a Stavropol (search) region emergency official said. He said that authorities had identified 30 of the dead and that 151 people remained hospitalized late Friday.

It was unclear whether the homicide attacker was included in the death toll.

The Federal Security Service said that along with the remains of the suspected bomber, unexploded grenades and remnants of a bag believed to have carried the bomb were found. The bomb was filled with shrapnel, prosecutors told Russian media.

Southern Russia's chief prosecutor, Sergei Fridinsky, suggested links to the other bombings, some of which were carried out by women. He said the explosives were similar to those found in belts worn by suicide bombers in some earlier attacks, most of which were blamed on Chechen rebels.

"We will find those who did it," said Interior Minister Boris Gryzlov, calling the attackers "beasts" as his voice trembled in televised comments. "The earth will burn under their feet."

President Vladimir Putin called the attack "an attempt to destabilize the situation in the country on the eve of parliamentary elections" Sunday.

As with all attacks that Russian authorities suspect are linked to Chechnya, Putin equated the blast with the "international terrorism" that he said "has challenged many countries and continues to represent a serious threat for our country."

"It is a ruthless, serious, treacherous enemy," he said.

Condolences flooded in from around the world. U.N. Secretary-General Kofi Annan expressed dismay at the "vicious attack," and European Commission President Romano Prodi said Russians should not let the bombing keep them from voting Sunday.

"We resolutely condemn this latest terrorist act," U.S. State Department spokesman Adam Ereli said.

Representatives of Aslan Maskhadov, a rebel leader and former Chechen president who considers himself the rightful head of Chechnya, denied responsibility for the explosion in a statement distributed to news media.

"We repeat that the Chechen government is guided by the principles of international humanitarian law," the statement said. "We therefore condemn any acts of violence that directly or indirectly target the civilian population anywhere in the world."

The attack was the second on the railway line linking the cities of Kislovodsk and Mineralniye Vody in the tense region that surrounds Chechnya.

Six people were killed in two blasts on the same line in September. No group claimed responsibility for those attacks.

The deadly bombings of the past year -- and a Chechen rebel hostage-taking raid on a Moscow theater in October 2002 -- have exposed the inability of Russian authorities to ward off homicide attacks, a tactic that was rarely used by Chechen rebels during the first separatist war in the region in 1994-96.

A suicide truck-bomb attack last December destroyed the headquarters of Chechnya's Moscow-backed government and killed 72 people, and another killed 60 at a government compound in the region in May. Later that month, a woman blew herself up at a religious ceremony, killing at least 18 people.

In June, a female homicide attacker detonated a bomb near a bus carrying soldiers and civilians to a military airfield in Mozdok (search), a major staging point for Russian troops in Chechnya, killing at least 16 people. A truck bomb in August, also in Mozdok, killed 50 people at a military hospital.

In Moscow, a double homicide bombing at a rock concert in July killed the female attackers and 15 other people, and an explosive device a woman brought into downtown Moscow less than a week later killed an expert who tried to defuse it.

Russian forces have been bogged down in Chechnya since 1999, when they returned following rebel raids on a neighboring Russian region and a series of deadly bombings that Russia blamed on the militants. Russian troops had withdrawn from Chechnya in 1996 after a 20-month war that ended in de facto independence for the devastated region.