BERLIN — German police on Monday said that “several people” had been injured in a rare campus shooting in the university town of Heidelberg in the country’s southwest.

       The “single perpetrator” is dead, the local police force said on Twitter. The attacker opened fire with a “long gun” in a lecture hall, it said, without giving further details.

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       Police believe the shooter to have acted alone, German news service DPA reported.

       Police had earlier warned people to stay away from the campus as it launched a “large scale” response to the shooting. Heidelberg University, established in the 14th Century, is the oldest in Germany.

       Vanessa Guinan-Bank in Berlin contributed to this story.