Berlin - A former pupil went on a shooting spree at a school in south-west Germany on Wednesday, killing 15 people before shooting himself in an exchange of fire with police.

The 17-year-old gunman killed nine students and three teachers, all but one of them female, at the school in Winnenden, near Stuttgart, in one of the worst incidents of its kind in Germany.

Police said the teenager also killed an employee at a nearby psychiatric clinic before hijacking a car and driving 40 kilometres to the town of Wendlingen where he killed two employees at a car showroom before shooting himself in the head after being cornered by police.

Germany's shooting happened the day after at least 11 people were killed in a similar shooting spree in the US state of Alabama.

The German teenager, who has not yet been named, was wearing a black combat uniform, was armed with a pistol when he walked into the Albertville secondary school at 9:45 am (0845 GMT).

Witnesses said he went into three classrooms and opened fire at the students without saying a word. The youth was a pupil at the school until 2007.

"A voice called out, 'Attention, there's someone running amok. Call a doctor'," a young pupil told the television news channel n-tv.

The dead students were aged between 14 and 15. Some still had pens or pencils in their hands, police said. A number of pupils were also injured in the attack, the motive for which was not immediately clear.

The gunman was reported to be the son of a local businessman who possessed a weapons licence and owned 18 firearms. Police searched the family home where the youth lived with his parents and found one of the guns missing along with 50 rounds of ammunition.

Police sealed off the school and the town centre of Winnenden, 25 kilometres north-east of Stuttgart. Some 580 pupils were in the building at the time and remained there for four hours until news of the gunman's death was confirmed shortly after midday.

Officials immediately began providing counselling to the distraught students, some of whom tried to contact their parents by mobile phone to tell them what was happening.

Germany's worst school shooting occurred in 2002, when a 19-year- old high school student went on a rampage in Erfurt, killing 12 teachers, two students, a school secretary and a policeman before killing himself.

German President Horst Koehler sent his condolences after Wednesday's shooting. Chancellor Angela Merkel expressed her "deep shock and horror" at the killings.