A male 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, managed to get from the enclosure to an adjacent storage building, where it attacked the 43-year-old keeper, said police spokesman Stefan Kirchner.

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

The zoo’s director used a rifle to shoot the animal dead through the storage building’s skylight before it could make its way to the visitor areas, he added.

Kirchner said it was unlikely that members of the public had witnessed the incident, which occurred around noon (1000 GMT; 5 a.m. EDT) Saturday.

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

The newspaper reported on its website that the tiger was a male It said a planned late-night opening of the zoo has been canceled.