Nine persons, including four employees of the Oreva group, were arrested by police on Monday and charged with culpable homicide not amounting to murder in connection with the Morbi bridge collapse case, a senior official said.

The Oreva group had bagged the contract to maintain and operate the British-era bridge that collapsed on Sunday evening, killing 134 people.

"Of these nine, two work as managers, while two work as ticket booking clerks (all four employed by Oreva group) at the bridge site. We will conduct a thorough inquiry and will not spare the guilty," said Range IG Ashok Kumar Yadav at a press conference.

The other five accused include two repairing contractors hired by the Oreva group and three persons working at the bridge as security personnel, said Yadav.

Earlier in the day, the senior IPS officer said the death toll from the bridge collapse has mounted to 134.

Police have registered an FIR (first information report) on charges of culpable homicide against agencies given the task of maintenance and operation of the bridge. The case was registered in Morbi under Indian Penal Code Sections 304 (punishment for culpable homicide not amounting to murder) and 308 (attempt to commit culpable homicide), police said.

The FIR, lodged by 'B' division police inspector Prakash Dekivadia, stated the bridge over the Machchhu river was not in use for nearly eight months as the local administration had roped in a "private agency" for its maintenance.