Three security guards died and another was injured today in what police said was a gunfight between former colleagues in Madrid's central post office.
The man who started the incident turned his gun on himself afterwards.
Officials said the 35-year-old man was on sick leave and that he was known to have had problems at work with his colleagues.
One security guard died at the scene and the other at hospital.
A fourth guard, a 50-year-old woman, was being treated for life-threatening injuries, said a spokesman for Madrid's accident and emergency service SAMUR.
"It has been an episode of insanity caused by a disturbed vision of this man's labour problems" said Constantino Mendez, an Interior Ministry representative for the Madrid region.
An investigation was under way.
AP