Two bombs exploded on a train headed from India to Pakistan, sparking a fire that swept through two coaches and killed 66 people in an attack that officials said Monday was aimed at undermining the peace process between the rivals.

Witnesses described a scene of horror as panic-stricken passengers were trapped in one of the burning cars even after the train stopped, just before midnight Sunday in a rural area in northern India. The screams of the victims filled the night, then were drowned out by the roar of the flames.

Most of the dead were Pakistani, said Railway Minister Laloo Prasad. Dozens were injured.

Authorities searching undamaged train cars said they found two suitcases packed with crude, unexploded bombs and bottles of gasoline, apparently similar to the devices that had exploded.

"This is an act of sabotage," Prasad said. "This is an attempt to derail the improving relationship between India and Pakistan."

A Home Ministry official, speaking on condition of anonymity because of the ongoing investigation, said no suspects had been ruled out — from Kashmiri separatists to Hindu extremists.

The attack came two days before Pakistani Foreign Minister Khursheed Kasuri was to arrive Tuesday in New Delhi for talks, and Pakistani President Gen. Pervez Musharraf said both countries should move forward with peace efforts.

"We will not allow elements which want to sabotage the ongoing peace process and succeed in their nefarious designs," Musharraf was quoted as saying by state-run Associated Press of Pakistan.

Kasuri called the attack a "terrible act of terrorism," in a television interview, adding that "the peace process must go on with greater vigor and greater determination."

The fire engulfed two coaches of the Samjhauta Express, one of two train links between India and Pakistan, just before it reached the village of Dewana, about 50 miles north of New Delhi, said Babu Lal, a railway worker who heard the explosions that sparked the flames. The blaze spread quickly as the train kept moving.

The driver of the train apparently had no idea what was going on.

"I saw flames leaping out of the windows," said Vinod Kumar Gupta, the assistant manager in the Dewana station, and he ran to pull the signal ordering the train to stop.

The train — which normally races through this region at about 55-60 mph — took another five minutes to halt in nearby countryside, Kumar said.

As on most Indian trains, the windows of many cars are barred for security reasons, sealing in many victims, and officials said at least one door was fused shut by the intense heat.

"We couldn't save anyone," said Rajinder Prasad, a laborer living near the tracks who raced with his neighbors to the fire, scooping water from a reservoir and throwing it at flames that shot high above the carriages. "They were screaming inside, but no one could get out."

Eventually, he said, the screaming stopped.

"From the less-damaged coach, some people were seen jumping out with their bodies on fire," Bharti Arora, superintendent of the Haryana state railway police, told reporters.

But in the rear car, where flames were more intense, few escaped.

Some people remained alive in the burning cars for nearly half an hour after the first explosion, said Rakesh Gautam, a reporter with the Hindi-language newspaper Dainik Jagran, one of the first people to arrive at the scene.

"Inside you could see trapped people trying to break windows, but after a while the train got so hot that the efforts stopped," he said.

Fire engines arrived about 45 minutes later, but it was another two hours until the flames were extinguished.

Arora put the death toll at 66. At least 30 passengers were hospitalized, officials said, with a dozen critically injured people brought to New Delhi.

The train was traveling from New Delhi to Atari, the last station before the Pakistan border. At Atari, passengers switch to a Pakistani train that takes them to Lahore, Pakistan.

Indian Foreign Ministry spokesman Navtej Sarna said officials from Pakistan's high commission were heading to the scene.

"The entire process is being carried out in cooperation with Pakistani authorities," he said. "The government will make every effort to bring to justice the perpetrators of this heinous crime."

Frantic relatives flocked to New Delhi's main railway station, where they found only a handwritten list on a bulletin board with the names of 13 injured and one identified corpse.

Mohammed Wasim Khan, who had left his uncle and two young nephews at the station Sunday, said railway officials brusquely told him to take a train to the scene of the blast if he wanted more information.

"What am I going to tell my cousins?" he said, crying. "What will I tell them?"

The New Delhi-Lahore train link was suspended during tensions that nearly led to war following a 2001 attack on the Indian Parliament that India blamed on Pakistan.

Relations between the nuclear-armed neighbors have warmed in recent years, and the train service — restarted in 2004 — is one of the most visible results of the peace process.

Their enmity focuses on Kashmir, a largely Muslim Himalayan region divided between them but claimed by both. More than a dozen militant groups have been fighting in Indian Kashmir for nearly two decades, seeking the region's independence or its merger with predominantly Islamic Pakistan. More than 68,000 people have died.

Within hours of the fire, authorities detached the burned coaches and the rest of the train left for the border.

Monday's blaze revived memories of earlier train deaths, including July train bombings in Mumbai that killed more than 200 people. Police blamed those attacks on Lashkar-e-Tayyaba, a Pakistan-based Islamic militant group, as well as the Students' Islamic Movement of India, a banned Indian group. Officials also alleged Pakistani intelligence was involved, but Pakistan denies that.

In 2002, Hindu-Muslim riots broke out after a train fire killed 60 Hindus returning from a pilgrimage. Muslims were blamed for the fire, and more than 1,000 people, mostly Muslims, were killed by Hindu mobs.

About 84 percent of India's more than 1 billion people are Hindu. Muslims account for about 14 percent.