Arrests have been made after four workers were attacked on Auckland's rail network in the past week, sparking a union call for better protection.
One had his jaw broken, allegedly by a man who jumped on the outside of a moving train.
The other is said by the Rail and Maritime Transport Union to have suffered a fractured eye socket after being overpowered by a group of youths on Saturday afternoon, at a west Auckland station.
A third was also allegedly roughed up at another western station on the same afternoon, having had a ticket machine hit out of his hands and his glasses knocked off his head as he bent to pick up the machine, said union organiser Stuart Johnstone.
He understood the same group, possibly early teenagers, may have been responsible for both attacks that day.
Mr Johnstone said the worker with the broken jaw was one of two staff attacked at Avondale on Wednesday, after passengers had been asked to leave a faulty train needing to be returned to its depot.
The injured worker, a KiwiRail fitter, had been sent out to fix a brake problem but as the train started moving out of the station a man jumped onto it.
"He jumped on the outside of a moving train, putting his life in danger,'' Mr Johnstone said.
"They got him inside, but he let off a fire extinguisher and caused all sorts of problems. Then in a scuffle he hit this guy [the fitter] twice.''
The second victim in that incident, and the two workers allegedly attacked on Saturday, are employees of rail operator Transdev.
That company said last night that "as a result of close liaison with the police", arrests were made quickly in both injury cases, which followed moves to beef up security after earlier incidents.
Managing director Terry Scott said the company was extremely concerned about the assaults, and was taking legal advice about possible civil action against offenders, separate to criminal proceedings.
"The safety of our customers and staff is always our primary concern,'' he said.
"Our staff deserve to have a safe environment and to go home in the same condition they came to work.''
Mr Scott said the company increased coverage of security staff on trains late last year "in response to incidents of antisocial behaviour that became evident in some areas.''
It had created the role of security manager to liaise with the police and Maori wardens to attend rapidly to incidents on an increasingly busy rail network.
But Mr Johnstone said that appeared not to have been enough.
"It clearly hasn't made enough difference - it's more of a bureaucratic solution rather than one on the ground,'' he said.
"Transdev is looking at prosecuting as far as it can to protect staff, but there is a growing feeling not enough has been done to protect the staff from these sorts of assaults.''
Saturday's incidents were at the Ranui and Swanson stations, but he was unclear which worker was assaulted where.
He understood the worker with the fractured eye socket, a train manager, was kicked and punched after being surrounded by eight youths.
The second, a ticket inspector, was shaken but uninjured.
Mr Johnston said the union was meeting this week with Transdev, and was calling on Auckland Transport as the contractor of passenger rail services to join the company to ensure everything possible was being done to protect staff.
KiwiRail spokeswoman Kimberley Brady said the Government operator was very concerned about the serious assault on an employee "who was simply trying to do his job.''