“The victims were drugged with ketamine,” Kurucova was quoted as saying. “They woke up several hours later not clearly remembering what exactly happened to them.”

The criminals robbed the women, local police reports. A girl aged 9 became the fourth victim of the gang in broad daylight, but the criminals took nothing from her. Police are now searching the area.

The incidents follow a series of attacks of this sort, police say. The first happened in August, with three other taking place over the past two weeks.

Ketamine is commonly used in animal surgery. It possesses strong hallucinogenic properties and can lead to a loss of consciousness. When injected it works as an anesthesia. It is also sometimes used as an antidepressant.