Winnenden, Germany  - The small town of Winnenden in south-west Germany struggled to come to terms Thursday with the school bloodbath in its midst that left 16 dead.

"Why?" was the question most commonly asked by students as they paid tribute to the pupils, teachers and innocent bystanders gunned down by Tim Kretschmer, 17.

"What did you have against them?" read a message at one of the tables decorated with flowers and candles that schools in the vicinity set up for pupils to pay their respects.

"I am totally shocked," said an 11-year-old, as she walked across the playground of a school just a few hundred metres away from the Albertville secondary school where Wednesday's attack took place.

Kretschmer killed nine students and three teachers before fleeing and gunning down three other people until he shot himself after being cornered by police 40 kilometres away.

The Albertville school remained closed as psychiatrists provided counselling to traumatized students and teachers as well as the families of the victims.

Counsellors were also present at other schools where "we could talk with them all day about what happened," said one girl who saw the body of a gardener shot dead by Kretschmer as he fled.

"It's really painful to think about it," said another girl.

Some of the schools cancelled lessons for the rest of the week, but teachers were there to discuss Wednesday's events with pupils.

"The children were upset," said one teacher. "It's important to let them give vent to their feelings."

The town is planning a memorial service for Friday, but the major remembrance ceremony will take place on March 21 when Chancellor Angela Merkel and President Horst Koehler are due to attend.

Police disclosed that one of their officers called to the scene of the attack learned over the police radio that his wife, a teacher at the school, may have been one of the victims.

It later turned out that she was among the dead, possibly gunned down as she tried to shield her class from Kretschmer, who was a pupil at the school until last year.

The youth was first identified as the gunman by three former classmates who survived the bloodbath by climbing out of a school window and alerting police.

The children described how Kretschmer came into their classroom, shot dead four girls and left, only to return a short while later.

He then started firing indiscriminately as the students dived for cover behind their desks. Police arrived on the scene shortly afterwards.

Officials said earlier the gunman was a troubled youth with a love of guns who had been undergoing treatment for depression.

He apparently acted out of revenge, believing his former schoolmates had made fun of him and did not take him seriously.

Officials said there had been threats to six other schools in region after Wednesday's shooting, prompting police to increase surveillance of school buildings.

It was Germany's worst school bloodbath since April 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. (dpa)