A guard was attacked by an inmate wielding a stool in a Stanley Prison clothing workshop yesterday. The assault occurred at about 11.30am when the Correctional Services Department (CSD) technical instructor Yeung Kwan-wai, 41, criticised the 42-year-old prisoner's workmanship. A CSD spokesman said the prisoner hit the instructor over the head with a fibreglass stool. Another inmate was hurt when he tried to stop the assailant from hitting the instructor a second time, the spokesman said. The attacker was subdued by other CSD officers. There were about 30 other prisoners and four staff in the workshop when the incident happened. Mr Yeung was treated for head injuries at Eastern Hospital and later discharged. The injured prisoner was treated at the prison clinic. The attacker was jailed last October after being sentenced to four years and 11 months for robbery and possession of dangerous drugs.