The tragedy took place amid rain in the city around 10.40 am when the FOB was heavily crowded, a police official said.
Police suspect a short-circuit with a loud sound near the FOB led to panic and people started running, resulting in the stampede.
More From This Section
Three persons were brought dead to the KEM Hospital in Parel. Besides, around 20 persons were injured and rushed to various hospitals, an official of the Brihanmumbai Municipal Corporation's disaster control room said.
Officials of the railway, police and fire brigade rushed to the site to carry out the rescue operations.
Further details are awaited.