"We condemn these attacks in the strongest possible terms. Our thoughts and prayers go out to those who have lost loved ones and friends in these attacks," State Department spokesman Sean McCormack said at a briefing.

"These are senseless acts of violence designed to strike at those innocent people who were just going about their daily lives, people who were commuting home on a train. It is a terrible tragedy for the people of India," McCormack said.

The U.S. government is ready to provide any assistance to India if needed, McCormack added.

A series of explosions in Mumbai on Tuesday have at least killed 138 people and wounded hundreds.