Police on Tuesday searched for the source of mysterious poison fumes in central Japan that left seven people dead, 56 sick and killed dogs in the street and fish in at least one pond.
Residents of the area in Nagano Prefecture, northwest of Tokyo, said they began calling ambulances late Monday night, complaining they smelled gas and felt sick.Police said they arrived on the scene around midnight to find several people collapsed on the street or on stairs leading down from their homes.
Five people were found dead in their homes and two others died soon after being taken to a hospital. Medical officials said 56 people were being treated for poisoning in the hospital Tuesday, three of them in serious condition.
"About 11 p.m. I went out to buy a can of juice and I saw some kind of a fog coming up in a cloud from the ground," said 16-year-old victim Shingo Fukazawa. "I walked along for a while and then my eyes got sore and I felt bad so I went to the hospital."
Authorities said several dogs and pigeons were found dead in the street and fish in at least one nearby pond also died.
Local investigators said most of those affected lived in the same residential block and that those who had the windows of their apartments opened became sicker than those who had them closed.
Police and medical officials said they have been unable to isolate the cause of the poisonings and were checking water supplies in the area.
The Matsumoto Waterworks Bureau said its staff had checked the supply and found nothing unusual.
Most of the victims complained of a headaches, nausea and deterioration of their vision.
Blood tests showed the enzyme cholinesterase, important for the nervous system, had dropped to between one-quarter and one-half the normal levels in most of the victims, medical officials said.
Dr. Manabu Seki, who was treating some of the victims at the city's Josai Hospital, said medical officials suspect the victims suffered some form of organic phosphor poisoning.