Namdaemun police investigating the deadly car crash that killed nine people on Monday evening said Wednesday that the vehicle began speeding from a hotel entrance after exiting its underground parking lot.

In an initial analysis of an event data recorder -- a device installed in vehicles that records technical vehicle and occupant information for a brief period before, during and after a crash -- the police were said to have found that the driver was driving at high speed after leaving a hotel near Seoul City Hall.

Police, however, declined to provide further information on the exact speed of the vehicle at the time of the accident as the investigation is still ongoing, vowing a swift probe into the case.

Officials corrected their earlier report at a press briefing on Wednesday, clarifying that what they initially identified as tire marks was actually engine coolant, also known as antifreeze.

In addition, police have requested an investigation of the EDR, black boxes and security camera footage from the accident site to verify the driver's claim of a vehicle malfunction, as well as a thorough analysis of the car by the National Forensic Service, which will likely take at least one or two months. However, the investigation could be expedited considering the gravity of the case.

By analyzing footage from nearby cameras, officials also confirmed that the auxiliary brake lights had not turned on when the vehicle was driving on the wrong side of the road.

Chung Yong-woo, a senior police officer at Namdaemun Police Station, told reporters during a briefing that another injury had been reported as being caused by Monday's crash in central Seoul, bringing the total number of casualties to 16, including nine people who died. The injured person was not present at the scene as he was accompanying another victim to the hospital and did not report his injury to authorities at the time, the officer said.

The injured person had sustained a minor injury and was a colleague of two employees of the Seoul Metropolitan Government who died in the accident, according to reports citing authorities.

The 68-year-old driver, identified by his surname Cha, barreled into pedestrians late Monday after leaving a hotel to attend a family event. Soon after the accident broke out, the driver reportedly called his colleague twice, and said a crash had occurred due to unexpected acceleration and that the brakes didn't work.

The accident took place at an intersection near Seoul City Hall at 9:27 p.m., when a Genesis sedan plowed through a sidewalk guardrail and struck people waiting to cross the road. At the time of the incident, the vehicle was driving the wrong way on a one-way street. It collided with two cars after hitting the pedestrians, Chung explained.

Asked about allegations that the driver got into the accident after getting in a fight with his wife, who was with him at that time, Chung said the rumor was not true.

While all eyes are on whether a sudden unintended acceleration was to blame for the deadly car crash or whether it was due to careless driving, police said they would question the driver as soon as his physical condition improves. He is being hospitalized with broken ribs.

The wife, who was in the vehicle with the driver, told police in the first round of interrogations that "the brakes didn't work."

Meanwhile, the Seoul Metropolitan Government on the same day said it would team up with the Korean National Police Agency to discuss ways to strengthen driving license aptitude tests for senior citizens, as well as encourage elderly people to give up their licenses, as the number of car accidents across the nation involving older drivers has been on the rise.