A senior politician in India's financial capital Mumbai was shot dead on Saturday, weeks ahead of key state elections, with police probing the role of a notorious crime gang.

Baba Siddique, 66, a local lawmaker and former minister in Maharashtra state, was shot multiple times in the chest outside his son's office in Mumbai, Indian media reported.

Maharashtra's deputy chief minister Ajit Pawar, from the same party as Siddique, said he was "shocked" by the "cowardly attack."

The Hindustan Times newspaper reported that two suspected attackers had been arrested, and police were searching for another.

Broadcaster NDTV said the two suspects claimed they were part of a gang run by Lawrence Bishnoi, who is in jail accused of running a crime gang that has carried out multiple killings.

The shooting comes just weeks after Siddique's security detail was upgraded after he received death threats, and ahead of elections slated for later this year.

"The incident will be thoroughly investigated and strict action will be taken against the attackers," Pawar said in a statement. "The mastermind behind the attack will also be traced."

Siddique was close to several Bollywood stars and was known for throwing grand parties. (AFP)