WINNENDEN, Germany (CNN) -- A gunman dressed in military gear killed 15 people Wednesday in a shooting spree in Germany before he was shot dead by police, police spokeswoman Renate Roesch told CNN.

Police launched a manhunt for the 17-year-old gunman who was said to be heavily armed.

The gunman, 17, began his rampage at a school where he used to be a student in Winnenden, a small town near Stuttgart.

"The suspect broke into the school. He went into the classroom and shot wildly around himself and left the building and fled on foot," Hans Ulrich Stuiber, another police spokesman, said.

Three teachers and nine students were killed at the Albertville-Realschule Winnenden, Roesch said. The shooting, which began around 9:30 a.m., lasted about two minutes, police said.

On his way out of the school, the gunman killed a person who was working in a hospital nearby, then hijacked a car, taking an occupant hostage.

He drove to the nearby town of Wendlingen, kicking the hostage out of the vehicle on the way, said Leo Parzinger of the Wendlingen police.

He then killed two more people before being killed himself in a shootout with police, authorities said.

At least seven people were injured in the shootings -- five people in Winnenden and two police officers in Wendlingen -- Roesch added. She was unable to say how serious the injuries were.

The families of the dead have been informed and are receiving counseling, she said.

She declined to name the gunman.

German Chancellor Angela Merkel is planning to make a statement about the incident later in the day, her office said.