Police say the number of casualties in Monday night's deadly car crash in Seoul has increased by one.

Jeong Yong-woo, the head of the Seoul Namdaemun Police Station's traffic department announced in a press briefing on Wednesday that the number of injured pedestrians rose to seven after it was confirmed that one of the victims was rushed to a hospital without being reported to officers on the scene.

The additional injured victim was a co-worker of two city hall officials who died in the deadly accident.

According to the official, the total number of casualties increased to 16, including nine dead and seven injured.

Jeong also said the police will speed up its probe of the accident as soon as the injured perpetrator's physical condition improves, adding that they have requested the National Forensic Service(NIS) to investigate the perpetrator's car to see if his claims of sudden unintended acceleration are true.

An NIS analysis of a vehicle's event data recorder(EDR) usually takes one to two months, but the police said the agency will likely fast track the process, given the seriousness of the case.