NEW DELHI, Nov. 27 — Gunmen attacked three luxury hotels, a hospital, a train station, a movie theater and other buildings in Mumbai late Wednesday, killing at least 80 people and wounding more than 300 in a rampage through India's financial capital, police said.

The attackers took dozens of people hostage, and witnesses said they were seeking out Americans and Britons. An unknown group asserted responsibility in e-mails to India's news media.

The gunmen, armed with explosives, lay siege to two of the hotels all night. Troops stormed in to rescue people, some of them foreign nationals, trapped inside. The 105-year-old Moorish-styled rooftop dome of the landmark Taj Mahal Palace & Tower hotel was engulfed in fire, and flames billowed out of many rooms. One wing of the waterfront hotel was gutted. Seven hours after the first attack, firemen rescued more than 50 hotel guests and escorted them to ambulances.

The attacks occurred in the affluent southern quarters that are the heart of the financial district of this city of 15 million people. Hospitals were overwhelmed and sent out appeals for blood donations. Police said parts of the city remained under siege as of dawn Thursday. Guests were still trapped inside the 36-floor Oberoi Trident hotel, possibly as hostages. Commandos tried to storm the hotel and police battled the gunmen as hotel guests signaled to firemen from their room windows. The third hotel to be attacked was the Ramada, to the north.

The identity of the attackers was not clear. A group calling itself the Deccan Mujaheddin asserted responsibility for the attacks in the e-mails. Intelligence officials said they thought it was a new group and were unsure of its aims or identity. The purported group's name apparently refers to the Deccan Plateau, an area that spans eight states and covers much of central and southern India. The term "mujaheddin" suggests the attackers are Muslim extremists.

R.R. Patil, chief of internal security for the state of Maharashtra, said the gunmen came from the sea around 9 p.m. local time Wednesday, and a boat laden with explosives was later seized by police. About 9:25 p.m., eyewitnesses told reporters, two men with automatic weapons started firing outside the popular Leopold Cafe, after which the attackers moved toward the Taj Mahal hotel, firing at random as they moved to the city's main train station. Local trains were suspended after a high-security alert, and the police cordoned off the area, which is usually packed with night revelers at street food vendors and cafes. The hotel evacuated many guests, some of whom could be seen wheeling out their luggage, while some others fled down the fire escape in bathrobes.

Witnesses told reporters that the gunmen initially asked for Americans and Britons. "They were young boys, maybe 20-25 years old. They basically were saying they wanted anyone with British and American passports," said a Briton quoted by the Times Now television channel. "There were about 15 people, about half of which were foreigners. We went to the 18th floor. It became very smoky, and we escaped and ran down the stairs. They had guns, one machine gun and one rifle gun. They were in jeans and T-shirts. Just normal, casual."

A 34-year-old businessman, Ashish Jain, said in a phone interview that he was having dinner with his friends at the hotel's rooftop restaurant, "Souk."

"When I paid the bill and tried to leave, the hotel staff said there were terrorists in the lobby and that we could not leave. There were 150 of us on the rooftop, including some foreign nationals," he said. "It was really alarming to be trapped there for over four hours. We could feel the building shake with the explosions. We could see the smoke and the fire. People were panicking and crying. And finally the army and the police came and secured the fire escape exit, and we could get out."

An image of a gunman broadcast on television showed a young man with curly hair, a blue rucksack slung over his shoulder, wielding an AK-47 assault rifle, and wearing a black half-sleeved T-shirt and jeans.

Another security camera image captured at the train station showed two young men wearing jackets and backpacks, each carrying a weapon. The floors of the station were stained with blood where the gunmen had fired at the crowd.

Officials confirmed that two attackers were killed, and nine suspects detained. Eleven policemen, including the chief of Mumbai's counter-terrorism squad, Hemant Karkare, died in the fighting at the hotels.

Since May, a wave of bombings has ripped through public places in several Indian cities, killing more than 200 people. Some of the bombings were followed by claims of responsibility from a group calling itself the Indian Mujaheddin.

"Who they are is a matter that is still under investigation, because our first priority is to rescue the people trapped inside the two hotels. We do not have correct knowledge about how many people are still trapped. People are still inside their rooms," said Vilasrao Deshmukh, the chief minister of Maharashtra at a press conference in Mumbai. He also denied that foreign nationals were specifically targeted. "It is not right to say that they were only targeting foreigners. Most of the people killed were Indians."

In Washington, U.S. intelligence officials were closely monitoring developments in India while analysts studied the attacks for signatures of known terrorist groups. The starting assumption was that the attacks were linked to Islamic extremists, though not necessarily al-Qaida or other well-known groups.

"The sophistication of the attacks and the choice of targets put Islamic extremists at the top of the list," said a senior U.S. counterterrorism official. "They are the most natural suspects." But the official noted that the Indian government has been targeted numerous groups, some of which have mounted suicide attacks against public buildings. "It is still an unfolding situation, and any hard and fast conclusions would be premature," said the counterterrorism official, who insisted on anonymity because he was not cleared to talk about the events.

Private intelligence analysts noted that the attacks were markedly different from others that have occurred in India in recent weeks. Those attacks involved planted explosives detonated by remote control, and were aimed at soft targets such as religious temples, markets and train depots. Most of these incidents involved Muslim extremists operating under the name "Indian mujaheddin." By contrast, the attackers Wednesday night chose relatively harder targets — hotels — and were essentially suicide missions, they said. The relatively large number of gunmen also suggests an attack that was carefully and professionally planned, said Brian Genchur, spokesman for Stratfor, a private intelligence group.

"As opposed to trying to rile up extremist elements in India's Hindu and Muslim communities, the attacks in Mumbai are going after the country's tourism industry, spreading fear to Western tourists and businesspeople who frequent India, thereby hitting at India's economic lifelines," Genchur said in an e-mailed statement.

Mumbai, formerly known as Bombay, has been the scene of bombings that have killed hundreds of people since 1993. In the worst attack, 257 people were killed and more than 1,100 wounded in a series of 13 bomb blasts in March 1993. Indian authorities blamed Muslim extremists for the attacks on the city's stock exchange, trains, hotels and gas stations. After a long-running trial, 100 people were convicted of involvement in the bombings, which authorities said were carried out to avenge the deaths of hundreds of Indian Muslims in religious riots.

In 2003, more bombings attributed to Muslim extremists killed 52 people in Mumbai.

In July 2006, more than 200 people were reported killed in a series of blasts that ripped through railway trains and commuter rail stations in Mumbai. Police later filed charges against 28 suspects belonging to a Pakistan-based Islamic militant group called Lashkar-i-Taiba and a banned northern Indian organization called the Students Islamic Movement of India. Police charged that the Pakistani intelligence service was behind the bombings. Pakistan denied the accusation.

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Staff writer Joby Warrick in Washington contributed to this report.