This one is really odd. There were many cases of unverified rampage killings. Siquijor (32 people dead when a guy was running amok with a machete) is worthy mentioning. I still tried researching this case though several newspapers — Brazilian, Italian, German, Chinese but still no success.
For rampage killings on unusual circumstances, what comes to mind is the Cirumput amok case in 1988 (10 deaths and 2 injuries by a women running amok with his bare hands and bare foot). Women only identified as O.L, allegedy under the influence of black magic requested the help of a shaman who did gave a note with instructions on how to cure her, after returning to her home, she began praying, when the prayer ended, she began stomping on the children for three hours. When the crime was discovered the woman was severely beaten by neighbours and afterwards taken to hospital, where she claimed that the children were not dead, but in the care of Madam Haji (apparently some kind of spirit) on the summit of Mount Gede.
Other strange one is of a women on Soweto in 1982 who strangled her own child when she had given birth and began battering other infants, killing six of them.