Sacramento - A fired California security guard allegedly killed four of his former co-workers and left another handcuffed in a city zoo while he escaped in her car, police said yesterday. The Sacramento police spokesman, Sgt Daniel Hahn, said the suspect, Mr Joseph Ferguson (20), was still at large and believed to be armed and dangerous. Police said Mr Ferguson was fired from his job at Burns Security last week for unknown reasons, and allegedly made threatening calls to a co-worker on Saturday evening.