**A gunman armed with an assault rifle has shot at least three people at a factory in the city of St Louis, Missouri, US police said.**At least one person has been killed at the ABB Power electrical products plant, a fire department spokesman told AP news agency.
Another report said workers were hiding in offices and on the roof awaiting rescue, while the gunman was at large.
Police have surrounded the building and nearby roads have been closed.
The shooting began at 0630 local time (1230 GMT) police said.
Some local media said the gunman was an employee at the plant, but this was not confirmed.