NEW DELHI - An Indian fire official said at least 58 people were killed and over 100 injured on Saturday when three bombs ripped through markets in Delhi crowded with holidaymakers ahead of major Hindu and Muslim festivals.

The aide to Delhi Chief Minister Sheila Dikshit said at least 54 people were injured. Officials said it was too early to speculate who was responsible for what Prime Minister Manmohan Singh called a terorist act.

Security at airports and railway stations was stepped up. Some media reports said up to 10 suspects had been arrested, but there was no confirmation from police.

Prime Minister Manmohan Singh urged people to remain calm and said in a statement that "India will win the battle against terrorism." The statement was read on CNN by one of his top advisers, Sanjaya Baru, who said the explosions were the work of terrorists, but did not say who the government thought was behind them.

Home Minister Shivraj Patil said 39 people were killed in the blast in the Sarojini Nagar market. Jagtar Singh, a spokesman for the Delhi fire department said seven people were killed in the first blast, in the crowded central neighborhood of Paharganj and three were killed on a bus in the Govindpuri neighborhood. He had no further details.

A policeman, speaking on condition of anonymity because he was not authorized to speak to the media, said at least seven people were killed and 60 more were injured in the first explosion, in the central New Delhi neighborhood of Paharganj. At least 15 people were killed in a blast in the main market in the Sarojini Nagar neighborhood, New Delhi Television said.

Vir Singh, a spokesman for the city's fire department, confirmed that there also had been an explosion on a bus in the Govindpuri neighborhood.

He had no further details.

The Israeli embassy in New Delhi is on a heightened state of alert as workers attempt to locate any Israelis that might have been injured in the explosions.

The Foreign Ministry has opened a situation room in response to the blast. It can be reached at 02-5303155.

In addition, workers of Beit Habad, located near the main bazaar, made their way to the local hospital to where victims had been evacuated, in an effort to determine whether Israelis were among the injured.

One Israeli youth was reported to be lightly injured in one of the blasts, according to Israel Radio. The youth's family has been notified of his condition and he is expected to return to Israel later this evening.

Israel's ambassador to India has issued a statement calling on all backpackers to avoid frequenting markets.

Police said a fourth blast reported by some local televison stations was a hoax put down to firecrackers.

Witnesses confirmed hearing an explosion near the Sarojini Nagar market.

"The blast was so powerful, my house shook," said Kiran Mohan, a photo editor who lives about 200 meters (yards) away from Sarojini market.

The initial blast took place in the main Paharganj market in the evening, when it was filled with shoppers ahead of a major Hindu festival next week, the fire brigade said.

Paharganj is a busy wholesale market, dotted with small, inexpensive hotels frequented by foreign travelers, particularly backpackers.

All roads to the scene of the explosion were sealed off by authorities.

It remained unclear what caused the explosions.

While the Indian government faces opposition from dozens of militant organizations - from tiny fringe organizations to well-armed Kashmiri rebel groups - there was no immediate official word that the explosions had been caused by bombs.

In addition, fireworks are widely used to celebrate the upcoming Hindu festival, Diwali, and many markets are now crowded with stalls selling elaborate - and often very dangerous - fireworks.

Over 100 dead in India train derailment Rescue workers pulled 100 bodies from seven coaches of a passenger train that derailed and fell into a rain-swollen river in southern India on Saturday, railway officials said, warning that scores more people were still trapped inside.

"We have recovered 100 bodies so far. And some bodies may have been washed away" by the fast moving flood waters of the river, said Thomas Verghese, general manager of India's southern railway.

About 100 injured passengers had been rescued from the coaches, which derailed after floods washed away the tracks in the town of Veligonda in Andhra Pradesh state.