At least 80 people, including Anti-Terrorism Squad chief Hemant Karkare, were killed when terrorists struck with impunity in Mumbai in coordinated multiple blasts and gunfire in a dozen areas across Mumbai.

"These coordinated attacks on innocent civilians demonstrate the grave and urgent threat of terrorism," Obama's Chief National security Spokesperson Brooke Anderson said in a statement.

"The United States must continue to strengthen our partnerships with India and nations around the world to root out and destroy terrorist networks," he said.

"We stand with the people of India, whose democracy will prove far more resilient than the hateful ideology that led to these attacks," Anderson added.

In a statement, the US State Department condemned the terrorist attacks in Mumbai. "We are monitoring the situation very closely and stand ready to support the Indian authorities as they deal with this horrific series of attacks. At this point, we are unaware of any American casualties," it added.

The UN chief also strongly condemned the attacks, saying "such violence is totally unacceptable." He said that no cause or grievance can justify indiscriminate attacks against civilians and called for the perpetrators of the attacks to be brought to justice.