Was it the driver, the car, the road or some combination of those factors?

That’s the question on everyone’s mind following the deadly crash of a stretch limousine last Saturday in Schoharie. The crash killed 20 people, including four sisters and two brothers who were among 18 people, including the driver, in the limo. It also claimed the life of James Schnurr, 70, of Kerhonkson, who was standing in a parking lot into which the car barreled.

The National Transportation Safety Board said it was the worst traffic accident in the country in a decade. The NTSB is investigating the crash, along with State Police, in order to answer the question, which is really two questions:

1. What happened?

2. Who’s responsible?

State police Wednesday said they had at least partially answered the second question with the arrest of Nauman Hussain, 28, the operator of the limousine service. Hussain was charged with one count of criminally negligent homicide in connection with the crash. State Police Superintendent George Beach said Hussain hired a driver who didn’t have the proper license to operate the vehicle and the limo had been ruled “unserviceable” by state inspectors last month. “The sole responsibility for that motor vehicle being on the road on Saturday rests with Nauman Hussain,” Beach said.

With so many lives lost, the desire to place responsibility promptly is understandable and admirable and the fact that Hussain’s suitcases were in the car he was driving when arrested suggests police were wise to move quickly. But there is still much to know and the NTSB must be methodical, not rushed, in its investigation:

1. The driver. To start with the obvious, was alcohol or drugs involved? There has been no suggestion of this regarding the driver, but the group of friends was on the way to a birthday party. The driver’s expertise has been challenged — he apparently didn’t have the proper license for the oversized vehicle. But his widow said he had driven tractor-trailers for 20 years, was in good health and often complained about the condition of the vehicles he was given to drive.

2. The vehicle. It was taken off the road by the state because of an issue with brakes. Was it serious? Was it corrected? Were there other problems? Hussain’s company, Prestige Limousine, reportedly has a history of sloppy maintenance of its vehicles.

3. The road. It has a history of accidents. It is a steep hill that comes to a stop sign at a T intersection. The owners of the popular store into whose parking lot the limousine barreled said trucks often ran the stop sign, crossed the road and sped through the parking lot, even after the state banned large trucks from the road.

Let’s add a fourth unknown: the rules. Currently, drivers of stretch limos are required to wear seat belts, but passengers are not. Would seat belts have saved lives?

There is no way to heal the pain of such a tragic loss of life on a celebratory occasion no less. But a thorough, unhurried investigation that answers the questions of what happened and who’s responsible may offer some comfort and help prevent future tragedies.