TOKYO >> The daring jailbreak of a dangerous criminal wearing only his prison-issued underwear has sparked an intense manhunt in a southern Japanese city and prompted schools to advise children to travel in supervised groups until he is caught.

Nearly 800 police officers have been assigned to the hunt for the convict, Li Guolin, a Chinese national who had been jailed for shooting at an officer and stealing a squad car in 2005, according to the Hiroshima Prefectural Police. Officers on Thursday scoured train stations, bus depots and parks across Hiroshima city. Police also distributed the convict’s mugshot door-to-door and posted his description on the Internet.

The escape Wednesday was the first ever from the Hiroshima prison, said a penitentiary official who spoke on condition on anonymity because he was not authorized to speak to the media. Tadaaki Nakagawa, a corrections official with the Justice Ministry, said the last escape by an inmate from within a Japanese prison was in 1989.

The Hiroshima board of education warned students to travel in groups to and from schools for safety.

Li escaped from the prison by reportedly ducking out of an outdoor exercise session and scaling two walls. He was serving a 23-year sentence for attempted murder and other crimes.

He escaped in his white, prison-issued winter underwear, according to a police statement.

Japanese media reported that Li managed to climb over a wall inside the prison campus and then use scaffolding to get over the 16-foot (5-meter) outer wall, which was under construction for repairs. Sensors on the wall were turned off because of the repair work.

Li, believed to be the leader of a gang of armed robbers, was sent to the Hiroshima prison in 2008.