Doorstaff alerted the police to the car that is believed to have contained a bomb after it was parked outside a London nightclub.
The car was parked in the early hours this morning outside the Tiger Tiger on Haymarket.
It contained what police said "appeared to be a potentially viable explosive device".
If it wasn't for their awareness, it could have been sat there outside a club with 1,000 people in it Terry Neil, managing director of TSS, which provides doorstaff to Tiger Tiger.
Terry Neil, managing director of TSS, which provides doorstaff to Tiger Tiger, told the Times that security staff had called police at around 2am before evacuating the venue.
He said: "We work very closely with Operation Griffin, the anti-terrorism thing, and the boys have been briefed as to what they should do. They did what they were trained to do.
"If it wasn't for their awareness, it could have been sat there outside a club with 1,000 people in it. It's a very busy road."
The incident has led to disruption for local pubs and clubs.
A statement from the police said: "Police were called to reports of a suspicious vehicle parked in the Haymarket, SW1, shortly before 2am this morning (29 June).
"As a precautionary measure the immediate area was cordoned off while the vehicle was examined by explosives officers. "They discovered what appeared to be a potentially viable explosive device. This was made safe.
"The MPS Counter Terrorism Command has launched an investigation. The Haymarket is likely to remain closed for the foreseeable future."
A statement from Novus Leisure, which owns Tiger Tiger, said: "The vehicle was parked in one of the busiest parts of central London in the early hours of a Friday morning when many, many people were leaving various nightclubs and bars after an evening out.
"The police have said it would be pure speculation to say that the club was the target.
The police were called, and Metropolitan Police Explosives Officers went to the scene and examined the car. Like many other businesses in the area, our staff were asked to evacuate the building which we did calmly and successfully whilst the device was made safe. We would like to thank the Explosives Officers, who manually disabled the device, and in so doing so prevented any potential injury to the public.
Every member of our staff is trained and issued with guidelines on preventing and dealing with acts of terrorism. We have clear crisis management procedures in place and act on regular advice from The Home Office, Metropolitan Police and The Security Industry Authority (SIA).
Our first priority is always the safety and welfare of our employees and guests. We maintain strict housekeeping practices and encourage our staff to be highly vigilant at all times. Tiger Tiger has been trading for just over nine years and has a strong proven record on safety.
Many restaurants, bars and businesses on The Haymarket, in Trocadero and on Jermyn Street are experiencing disruption. We continue to liaise closely with the police and authorities and await further information."