Greater Noida, July 24 - Four armed men barged into a transformer manufacturing factory here and, after locking up five employees of the firm, robbed copper ingots and the guard's rifle, police said Friday.

The incident occurred Thursday midnight at the Macro Plast Ltd factory in the Surajpur Industrial Area of Greater Noida, police said.

'Four men armed with pistols and knives entered the factory premises. When the guard attempted to stop them, they took away his gun and locked him up in a room with four other employees of the company,' a police officer said.

'The robbers then loaded about a tonne of copper ingots into a waiting truck and fled the scene,' the police officer added.

When the factory manager Atul Sharma came to know about the incident Friday morning, he lodged a complaint with police.

'We have registered a case and the factory management is preparing an inventory of the stolen goods,' Superintendent of Police Surendra Verma said.