Assailants wielding a knife and a pair of scissors attacked a young woman walking home from church and cut off most of her waist-length hair, police said on Monday.

A man and a woman grabbed 19-year-old Simone Regina Penteado Sunday evening in the southeastern city of Araraquara and "threatened to kill her with a knife if she didn't stay still," police spokeswoman Natalia Rinaldi said by phone.

"The woman grabbed about 36 inches of Simone's dark brown hair and cut it off at the nape of her neck," Rinaldi said.

"It is obvious they will try to sell the hair to wig makers or to hair-transplant centers," she said. Rinaldi added that the thieves, who were still at large, could be charged with armed robbery which carries a maximum sentence of 15 years.

Rinaldi said she did not know if the robbery was related to a similar attack in Araraquara in February, when assailants cut some 12 inches of a 45-year-old woman's hair.