Two men, aged 17 and 20, are due to appear at Lower Hutt District Court on Tuesday charged with theft, and two teens have been referred to Youth Aid in relation to the cash box.
Police were also "very interested'' in the movements on Friday night of a blue Toyota Previa with a number of occupants in it around Pohutukawa and Cudby Sts between 9.30pm and 10.30pm.
Anyone with information about the car or the people in it is asked to contact police.
There was no CCTV cameras fitted to look over the bus depot, and the Government will not be drawn on whether they will launch an investigation into bus driver safety.
Tramways Union national secretary Gary Froggatt said something needed to be done to ensure the safety of bus drivers, as this incident was not isolated and bus drivers were being put at risk.
"I think the Government has a responsibility to assess the companies to provide safety and so does the Department of Labour and probably the Accident Compensation Commission; prevention is better than having something happen later on.''
As a result of Mr Curry's death security at bus depots had been stepped up in the evenings, but Mr Froggatt said more needed to be done.
"I think there should be an urgent conference called by the Government, similar to the taxi industry investigation,'' he said.
CCTV cameras were not a common feature at bus depots and that would be a cheap way to deter would-be robbers, he said.
Ministry of Transport land transport safety manager Leo Mortimer said it the Government could possibly launch an investigation into bus driver safety - similar to one which resulted in taxi cameras becoming compulsory after Hiren Mohini was stabbed to death by a passenger in Auckland in 2010.
But, he said bus driver safety was different to taxi driver safety because the bus industry was one of an employer/employee relationship, while the taxi industry was a collective of taxi owners operating in a cooperative environment.
Issues around bus driver safety had been raised in the past but Mr Mortimer said the Government found it was something the bus companies themselves, regional councils and the funding body should work together on.
Legislation did not prevent buses from having cameras, he said.
"I guess you could say that it's the Government's role to ensure that there is no legislative areas to them implementing the measures that they think would be needed and I think that at the moment there is nothing to stop any company from putting cameras in vehicles.''
The whole arrangement needed to be looked at, and the Government would look at whether there was some way it could assist with working with the current arrangements, and whether there were any impediments to the industry providing better protections.
"You look at it and you say what would the best preventative measures be and I think that's the question you ask before you decide who takes responsibility or what government's role is.''
In December Taxi Federation magazine executive director Tim Reddish said taxi drivers felt much safer after the mandatory introduction of security cameras.
The behaviour of alcohol-affected passengers had modified considerably because of their awareness of the cameras, Mr Reddish said.
Late last year NZ Bus said it was considering whether to cancel some services after a bus driver was attacked by a passenger.
Herman Curry was a regular late-shift bus driver, who had been working in the Naenae area for about eight years.
Tulipe Tofilau, whose husband worked with Curry, said she did not want her husband to work at night.
"It's not safe now.''
Another bus colleague, Tenari Moananu, said he thought Curry was refuelling his bus when he died.
Police enquiries into his death are continuing
