Twelve persons were also injured after a truck ploughed into pedestrians in Lower Manhattan in New York on Tuesday. The suspect has been arrested.
New York has been among the top favourite destination for Bollywood celebrities, who thronged the city this year when it hosted the International Indian Film Academy (IIFA) extravaganza.
Here's what the celebrities tweeted:
Madhur Bhandarkar: Shocked and grieved by the news of Manhattan attack. My deepest condolences and prayers for the victims and their families.
Vishal Dadlani: Terrorists do not have any religion except hatred. When we hate each other because of their deeds, they win. That's exactly what they want.
Vivek Oberoi: Strongly condemn the horrendous Manhattan attack. My prayers go out to those who lost their lives and loved ones in this terrible tragedy.
Nila Madhab Panda: Shocked!!! To hear about the Manhattan attack... Condemn it in strongest terms... My thoughts and prayers for everyone in New York.
Huma Qureshi: So sad, cowardly and inhuman! I will always (love) New York.
Kunal Kohli: How do we fight this? We have security at airports and malls. They use trucks, cars and knives on the street. How do we stop this? NYC strong.
Ashoke Pandit: Sad to know about the terrorist attack in New York. Condolences to bereaved families and will pray fr speedy recovery of d injured.
Esha Gupta: Thoughts and prayers for everyone in New York right now.