WINNENDEN, Germany (CNN) -- A gunman dressed in military gear killed 15 people Wednesday in a shooting spree in Germany, police said.



German shooter Tim Kretschmer, 17, targeted females during his rampage.



Tim Kretschmer, 17, began his rampage at a school where he used to be a student in Winnenden, a small town about 20 kilometers (12 miles) northeast of Stuttgart.



Most of the victims at the school were female -- eight female students, three female teachers and one male student, said Heribert Rech, interior minister for Baden Wuerttemberg region.



Rech said: "They were completely taken by surprise. Some of the victims still had their pens in their hands."



Kretschmer opened fire in three first floor classrooms, including a physics lab where a teacher was found dead behind her desk, Rech told a news conference.



Rech said police arrived in minutes. "This speedy intervention means they prevented further escalation of events."



The shooting at the Albertville-Realschule Winnenden school began around 9:45 a.m. (0845 GMT) and lasted about two minutes.



Student Louis Schweizer was in class when he heard the gunshots. "When I came out, I saw the shell casings lying around everywhere," he said.



His sister, Lisa Schweizer, also heard the shots. "It is a tragedy," she said. "One of my teachers was killed."



Another student told CNN: "We heard that someone was inside shooting. Then we also saw a teacher who had blood on his hands because he wanted to help a female teacher who sacrificed herself for a student -- she stood in front of a student to protect her." Read how students jumped from windows to escape



Fifteen-year-old Natta lost a long-time friend. "She was a very good friend of mine from soccer, and I knew her since we were four years old and it's very hard," she said.



Kretschmer did not shoot wildly, Rech said, contradicting earlier police statements, but hit most of his victims in the head.



As the first police arrived at the school, he fled and killed a person working in a hospital nearby, then hijacked a car, taking the driver hostage.



He drove towards the nearby town of Wendlingen, but the car crashed on a sharp bend, Rech said.



The driver escaped and called police as Kretschmer ran away and towards a car salesroom in Wendlingen where he shot a salesperson and a customer, Rech said.  Watch the gunman's deadly route »



"Police officers in civilian clothes opened fire and shot several times. The perpetrator tried to escape and was shot at least once in the leg. ... A little later he was found dead," he added.



It was not clear if he died from injuries received in the police shootout or if he committed suicide. Regional police chief Erwin Hetger said police thought he had killed himself.



Kretschmer was on the loose for three and a half hours after the incident began, police said.  Watch more about the shootings »



German Chancellor Angela Merkel said it was "inconceivable that within seconds school students and teachers have been put to death by this terrible crime."



"It is a day of mourning for the whole of Germany," she said in a televised statement.



Police did not know the motive for the shooting spree, CNN's Frederik Pleitgen reported from Winnenden.



"No one seems to have an explanation for why this happened," he said. "Police officers have heard that this young man didn't cause much of a buzz, wasn't someone who was negative or known for violence. They have no idea why he did all this."



Police raided his parents' home later and found they had a collection of 14 guns.



The pistol used in the killing was part of the father's collection, authorities said. German gun laws are fairly restrictive and require owners to control access to them. Do you think the gun control issue is taken seriously enough?



Rech said the guns were legally owned
Who did the gunman target? Name of the shooter? Who is the gunman? What did Angela Merkel say about the shooting? What German school was the site of a rampage? What was the length of the killing spree? Who called it a day of mourning for Germany? What gender were most of the victims of the gunman at the German school? What number of people were killed?
females Tim Kretschmer, Tim Kretschmer, "inconceivable that within seconds school students and teachers have been put to death by this terrible crime." Winnenden, about two minutes. Angela Merkel females 15
question: Who did the gunman target?, answer: females | question: Name of the shooter?, answer: Tim Kretschmer, | question: Who is the gunman?, answer: Tim Kretschmer, | question: What did Angela Merkel say about the shooting?, answer: "inconceivable that within seconds school students and teachers have been put to death by this terrible crime." | question: What German school was the site of a rampage?, answer: Winnenden, | question: What was the length of the killing spree?, answer: about two minutes. | question: Who called it a day of mourning for Germany?, answer: Angela Merkel | question: What gender were most of the victims of the gunman at the German school?, answer: females | question: What number of people were killed?, answer: 15