A masked gunman with explosives strapped to his body ran into a high school in northern Germany today and opened fire on teachers and students, wounding eight, police said.

A caretaker, a pregnant teacher and six students were reportedly injured as they tried to confront the man.

The assailant, identified in German press reports as an 18-year-old former student at the Scholl secondary school in Emsdetten, is believed to have killed himself after briefly negotiating with police and as commandos prepared to storm the building.

The attacker was armed with a machine gun and set off a series of explosions during the brief siege, filling classrooms with smoke. Around 20 people, most of them police officers, suffered from smoke inhalation.

His body, badly disfigured, was discovered on the second floor of the school, where he retreated after the police were called and surrounded the building. Police said several pipe bombs were also found by the corpse and it was unclear whether the man had killed himself or died during an explosion.

Bomb disposal experts were called to defuse the devices attached to the body before it could be properly examined. "He is still lying there because he’s wired up," Hans Volkmann, a police officer investigating the attack, said this afternoon.

A teacher at the school was quoted by German press reports naming the attacker as a former pupil called Bastian. Authorities would not confirm the identity but a spokesman for the state prosecutor's office said he believed that the man was known to the police..

The state prosecutor, Wolfgang Schweer, said police had discovered photographs on the internet showing the attacker in military-style uniforms brandishing weapons. He was facing trial tomorrow on weapons offences and left a suicide note that "indicates something of his motive," said Mr Schweer.

"He seems to have been frustrated by a lack of meaning in his life," Mr Schweer told a news conference. "We have no reason to think he had contact with any extremist groups. It appears that he was a loner who decided on his own to do this."

Witnesses said the attacker climbed out of a car and walked into the school yard at around 9.30am local time (0830GMT), opening fire immediately.

Pupils and teachers streamed out of the high school, near Muenster, near the Dutch border, and fled into the street and nearby fields as he entered the main building.

None of the injuries are thought to be serious. The school secretary telephoned the police and first patrol car arrived six minutes after the alarm was raised.

The rest of the 693 pupils at the school, which is for children aged 11-16, were evacuated safely, police said. German television news showed pupils crying in the streets outside Scholl high school, which is in a prosperous suburb.

Katja Weber, a 17-year-old student at the school, said the assailant was known for always wearing a black hat and coat. "He was an absolute loner," she said. "Guns were his hobby."

School shootings and murders are not without precedent in Germany. In 1999, a 15-year-old student stabbed his teacher 21 times after taking bets from his classmates, who did not believe he would do it. He was imprisoned for seven and a half years. In 2002, a former student killed 17 people, including himself, in a classroom massacre in the eastern city of Erfurt.

German school attacks

November 1999: a 15-year-old boy stabs his teacher to death in Meissen, eastern Germany, after accepting bets worth £250 from his classmates.

March 2000: a 16-year-old pupil at a boarding school in Branneburg shoots a teacher, who later dies, and himself after testing positive for cannabis and being threatened with expulsion. The student remains in a coma.

February 2002: a student expelled from a technical school in Freising, near Munich, kills three people and himself.

April, 2002: a pupil opens fire in a classroom in Erfurt, killing 16 people and himself after reportedly refusing to take a maths test.

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