A dust pan and a gripper are pictured in front of an evacuated apartment building in Herne, Germany, Aug 26, 2019. (CAROLINE SEIDEL / DPA / AP)

BERLIN  — An escaped cobra is on the loose in a city in western Germany, and authorities are still trying to figure out how far the reptile has slithered.

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Municipal authorities in Herne said the venomous snake was spotted Sunday morning in the hallway of a house where snakes were kept, and it may have left the building. Four houses on the street were evacuated as a precaution and people within a 500-meter radius were advised to exercise caution, leaving their doors and windows closed.

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Officials sprinkled flour in the building in hopes that the snake would leave a trail, and laid down two-sided sticky tape that could stop the reptile.

Police said Monday that the cobra's whereabouts are still unknown.