Hemant Sharma (22) from suburban Kalina and Dipshikha Gupta (20) from Virar drowned while Shekhar Gaikwad (22) from Kalina was still missing and search was on, police said.
Another member of the group, Monika Fernandez (21) from suburban Marol, was rescued and hospitalised. She was said to be out of danger, according to the police. Another boy who was with them remained safe as he did not into deep water.
Malvani police were investigating further, said Dhananjay Kulkarni, spokesperson of Mumbai Police.
The group of five friends went to the beach at around 3.30 pm for a swim. Four of them ventured into deep waters, and were pulled away from the shore by the low tide, he said.
However, a senior MCGM official said that civic body had taken enough preventive steps. "We have placed a huge sign outside the beach that gives a clear-cut warning. It is really sad that over-enthusiastic youth do not pay heed," he said.