Officials at a German zoo say that a male brown bear attacked and killed a female bear in front of horrified onlookers.

Christoph Langner, the director of the zoo in the northern coastal German city of Stralsund, said the incident occurred on Saturday afternoon.

He said Sunday that zoo officials are still trying to determine why the male, a Syrian brown bear named Balou, attacked the female, Klara.

Zoo spokesman Peter Koslik said that Klara arrived at the zoo two years ago and Balou about half a year later.

They were kept apart at first but were later brought together. Langner said the two had showed signs lately of having adjusted to each other.