BERLIN — A tiger escaped its enclosure at Cologne Zoo in western Germany on Saturday and killed a female keeper before being shot dead by the zoo’s director, police said.

The tiger slipped through a passage between the enclosure and an adjacent storage building, where it fatally attacked the 43-year-old keeper, said police spokesman Stefan Kirchner.

“It appears the gate wasn’t properly shut,” Kirchner said.

The zoo was evacuated and a SWAT team was called in, police said. But before it arrived, the zoo’s director managed to kill the tiger by climbing onto the storage building and shooting it through a skylight using a high-caliber rifle.

Kirchner said it was unlikely that members of the public had witnessed the incident.

“This is the darkest day of my life,” the zoo’s director, Theo Pagel, said.

Cologne Zoo is one of the oldest in Germany. It was founded in 1860 and houses some 10,000 animals comprising more than 700 different species.