Soon after, police were cordoning off all major roads, stopping even emergency vehicles because of reports that two attackers had hijacked a police van.
Among the victims was the head of the city's Anti-Terrorism Squad, Hemant Karkare, and two of his senior police officers, which complicated the response. Television footage showed Karkare donning a flak jacket and helmet minutes before heading into one of the hotels.
The military was quickly called in to help police.
News media reports said that gunmen seized the Mumbai headquarters of the ultra-orthodox Jewish outreach group Chabad Lubavitch overnight and that shots were heard coming from the building.
Representatives of the New York-based group referred questions to its Web site, which said the Israeli consulate had earlier been in touch with the rabbi who lived in the house, "but the line was cut in middle of the conversation. No further contact has since been established."
Hospitals in Mumbai have appealed for blood. As a sense of crisis gripped much of the city, schools and colleges announced that they would be closed today.
Unlike previous attacks in India this year, which consisted of anonymously planted bombs, the assailants last night were spectacularly well-armed and highly confrontational.
In some cases, said the state's highest-ranking police official, A.N. Roy, the attackers opened fire and disappeared. Indian officials said police killed four of the suspected attackers and captured nine.
Terrorism experts said the late-evening timing offered several potential advantages for the attackers. Security is generally more lax at that hour, as businesses prepare to close. There is less traffic in the congested city, making it easier to position a large number of attackers at disparate sites. And it allows the story to hit news cycles in Europe and North America, with global publicity a key objective among terrorists hoping to undermine stability and spread fear.
In Washington, the State Department immediately condemned the attacks, as did President-elect Barack Obama's transition team.
It was not immediately known who was behind the attacks. A previously unknown group calling itself "the Deccan Mujahideen" said it carried out the attacks, though there was no way to know whether the claim was real.
India has been hit by a succession of terrorist attacks over the past several months. Many of them were initially blamed on Islamist militants, although in recent weeks, police have pointed to a Hindu terrorist network as well, making several arrests.
