The Maharashtra Navnirman Sena (MNS) office in Sion-Koliwada was ransacked on Friday night. Seven office bearers have been injured in the scuffle.
Unidentified men stormed the office with swords at 9 pm. The unit chief of the locality, Ramchandra Devram, has also been injured.
“The injured have been admitted to Sion Hospital, but no one is critical,” said Vinod Kopkar, a party leader.
The police have ruled out any political motive and are investigating the incident.
The MNS is headed by Shiv Sena Bal Thackeray’s nephew Raj Thackeray.
On Thursday, some Shiv Sainiks had attacked an MNS worker in Parel after their candidate had lost to the MNS candidate in the constituency.
The MNS has been the spoiler for the Sena in this election and eaten into their votebank, especially in the areas of Mumbai and Thane.