NEW DELHI, India?- The riots by Muslim protesters in downtown Mumbai on Saturday, in which two people died and more than 40 policemen were injured, had taken Indian authorities by surprise, said local media Monday.

More than a thousand people who sparked the violence at Azad Maidan in central Mumbai were not a part of the protest groups, but probably came from the suburbs to cause riots, local daily The Hindu quoted internal police report as saying.

The mob were armed with petrol cans, plastic bottles filled with inflammable liquids, hockey sticks, iron rods and bamboos, triggering speculation about a planned conspiracy to deliberately inflict damages to India's financial hub.

The protest was initially aimed at communal violence in the northeast Indian state of Assam between Muslims and local Bodo people, and ethnic clashes in neighboring Myanmar between Muslims and Buddhists.

However, police officials have denied any terror angle to the incident or intelligence failure.

The police also claimed that adequate forces were present to control the mob.

Mumbai was subject to a terrorist attack in November 2008, in which 10 terrorists killed over 160 people.