"There is chaos everywhere. This must be a terrorist act as it happened in three places," senior Sena leader Manohar Joshi said after reaching Dadar, one of the three sites of the blasts.
"I want that the government take immediate steps and find out who are people behind the blasts," Joshi said.
Lyricist Javed Akhtar said "No words are strong enough to condemn the attacks.
"This menace called terrorism.... something has to be done. Something drastic. This is not acceptable," he said.
Explosions have been reported in south Mumbai's Zaveri Bazar, Dadar in Central Mumbai, and Opera House in Charni Road.