A former Japanese gangster held a woman hostage for nearly 24 hours in his home after shooting a policeman dead and wounding his own son, daughter and another police officer. The woman was reportedly the ex-wife of the gunman, Michiko Mori, who was still in the house in Nagakute, a residential suburb of the central city of Nagoya, according to Reuters.

The man, Hisato Obayashi, apparently is still holed up in the house, surrounded by about 170 officers, including riot police and special units. "We must push ahead with effective measures to control firearms, including steps against gangsters, so that such an incident won't happen again," Kensei Mizote, cabinet minister in charge of the police force, told reporters.

Hisato Obayashi, 50, is reportedly a former member of the Yamaguchi-gumi, Japan's largest crime syndicate. Obayashi was expelled from a gang 10 years ago, Mainichi Daily News reported.

"This is a gun crime that clearly threatens the peace of public life. It is absolutely unacceptable," Chief Cabinet Secretary Yasuhisa Shiozaki said Friday morning.

In Japan, handguns are strictly banned, and only police officers and other professionals such as shooting instructors can own them. Hunting rifles are also strictly licensed and regulated, and most illegal gun owners are mob members.

Obayashi shot his 25-year-old son, Kento, in the stomach and 21-year-old daughter, Risa, in the leg. Sergeant Kazuho Hayashi, 23, a member of the Special Assault Team (SAT), was shot dead and Sergeant Akifumi Kimoto, 54, was shot in the stomach.