Yokohama - Health authorities on Tuesday were trying to determine what killed 17 crows and one pigeon whose bodies were found on the street in Yokohama earlier in the day.

According to police, the birds were found dead at around 8 a.m. in a 200-meter radius in an entertainment district about 400 meters from JR Kannai Station. NTV quoted police as saying there were no external injuries on the birds.

Health authorities said there was no sign of bird flu and believe the birds must have ingested poison of some kind.