Authorities have raised the death toll to 121 in the chemical warehouse explosion in the northern Chinese port of Tianjin, while another 54 people remain unaccounted for.

The city government said Saturday that the death toll from the Aug. 12 disaster includes 67 firefighters, with another 37 firefighters missing. Eleven policemen are also among the dead and missing, making it the worst disasters for first responders in recent Chinese history.

Technicians have detected levels of cyanide as much as 356 times the safe level within a 3-kilometer-radius (1.8-mile-radius) evacuated area, although no abnormal contamination was found outside the area.

Small animals such as rabbits, pigeons and chickens have been placed in the disaster zone to test whether it is safe for humans while workers in hazmat suits clear the area.