Johannesburg - A murder case is being investigated after a Samwu shop steward was shot dead outside the union’s head office, allegedly by security guards, Gauteng police said on Tuesday.The shooting took place around 13:00 on Friday afternoon, when a group of people got into a scuffle with security while trying to enter Samwu’s head office in central Johannesburg, Lieutenant-Colonel Lungelo Dlamini said.No arrests had yet been made, he said.The SA Municipal Workers’ Union said the group had not made an appointment to be there. Their member, Elliot Manyosi, died at the scene."The national office bearers, on behalf of the union’s entire membership, convey their sincere and heartfelt condolences to the Manyosi family, his colleagues and general membership," spokesperson Papikie Mohale said.Nightclub bouncersThey will contact Manyosi’s family to see how they could help.Mohale said there were conflicting reports of how Manyosi was killed. Rival unions - the Democratic Municipal and Allied Workers Union of SA and the Municipal and Allied Trade Union of SA - said the workers arrived at Samwu’s office in an "orderly and disciplined" manner.However, Mohale said this was not the case."The people barged into the office and assaulted staff members prior to the alleged shooting. I don’t know what orderly means in this sense. Staff members were assaulted and physically ejected from the building."The two unions' general secretaries - Mohau Mokgatla and Kurt Ziervogel - said in a joint statement that "a team of so-called protectors" confronted the group. They resembled nightclub bouncers and Samwu employed them at "phenomenal cost", they claimed.Mohale said they had no bouncers, but employed security guards to ensure the safety of staff and union members.According to the two unions, two other workers were also shot and wounded. However, neither Dlamini nor Mohale were aware of anyone else who had been shot or injured.