Analysis: From our Foreign Editor
This is far from the first mass terror attack in Mumbai, India's sprawling financial capital. Just two years ago, 200 people were killed in bomb attacks on the city's trains, blamed on a Pakistani and Indian Islamist groups.
But last night's atrocity was different.
This was an extremely well co-ordinated strike, featuring teams of gunmen attacking specific targets.
These objectives were not just places sure to result in the maximum number of casualties, such as the crowded train station, but also symbolic locations: luxury hotels, restaurants popular with Westerners - and of course, the local Chabad house.
The gunmen, clearly trained for a suicide mission, took dozens of hostages, marking another level of escalation.
The name of the previously unknown group which has claimed responsibility -Deccan Mujahideen - does not tell us much. But this is clearly not just another attack fuelled by ethnic tensions, but one with a global jihadi element.
The West, in the form of Brits and Americans, and a Chabad centre, is under attack, alongside India.