A pickup driver’s drug use was the reason he crashed last year into an oncoming group of motorcyclists in New Hampshire, leading to the death of seven bikers, the National Transportation Safety Board found Tuesday.

The board unanimously approved a report that determined that Volodymyr Zhukovskyy's impairment from the drugs was the “probable cause" for him crossing the center line on a rural, two-lane highway and sparking the fiery crash.

Zhukovskyy was returning from delivering vehicles for a Massachusetts transport company and was towing an empty flatbed trailer.

NTSB investigators told the board that Zhukovskyy had drugs, including opioids, in his system. They also said witnesses had reported him driving erratically.

“Very sadly, the circumstances of this crash underscore the rising concern regarding the impact of multi-substance impairment on transportation safety,” NTSB member Thomas Chapman said during the virtual hearing. “Our own research in this area indicates the instances of drug-impaired driving is increasing at even greater rates than alcohol-impaired driving.”

Investigators ruled out cellphone use or weather as a factor. They couldn’t rule out that fatigue played a role but concluded its effects were unclear because of the drug use.

The crash happened June 21, 2019, in Randolph. The seven bikers were members of the Jarheads Motorcycle Club, a New England group that includes Marines and their spouses. The victims were from New Hampshire, Massachusetts and Rhode Island.

Zhukovskyy, of West Springfield, Massachusetts, pleaded not guilty to negligent homicide and driving under the influence. He remains in custody as he awaits trial next year. His lawyer didn't immediately respond to a request for comment Tuesday.

Last month, documents released by the NTSB revealed Zhukovskyy told authorities he regularly used heroin and cocaine but believed he was not impaired at the time of the crash. He told Massachusetts State Police that he had used heroin and cocaine the morning of the crash.

Zhukovskyy’s lawyers have argued an independent analysis showed one motorcyclist was drunk and was the one who hit the pickup and caused the crash.

Investigators found that some bikers, including the lead motorcyclist, were impaired by alcohol but that it wasn't the reason for the crash.

The NTSB also found Massachusetts contributed to the crash for failing to revoke Zhukovskyy's commercial driving license beforehand. If the Massachusetts Registry of Motor Vehicles had acted, Zhukovskyy's license would have been suspended June 10 — or 11 days before the crash — and restored July 25.

The registry failed to act on information provided by the Connecticut Department of Motor Vehicles about Zhukovskyy's arrest May 11 in a Walmart parking lot in East Windsor after failing a sobriety test — something that should have cost him his license.

It was later revealed that the state grappled for years without success to clear chronic backlogs in the processing of notifications sent by other states of infractions by Massachusetts drivers. Registry officials acknowledge that tens of thousands of such out-of-state notices have gone unprocessed for years, instead left to pile up in boxes in a state office.

Similar problems were found in Rhode Island, New Hampshire and at least six other jurisdictions, the NTSB found.

Zhukovskyy was driving for Westfield Transport at the time of the crash. The company had a history of violations, and NTSB investigators said the company's actions “clearly did directly impact the crash by allowing the driver to get behind the wheel at the time of the crash."

The company had no corporate safety program, no drug testing program and no records showing it had a system for service and repairs. A manager also admitted the company had lied to investigators about some of the driver logs that were reviewed.

A review by the Federal Motor Carrier Safety Administration also found more than two dozen violations by the company. Among other things, the company was accused of making fraudulent or intentionally false entries on inspection and maintenance records, using a commercial motor vehicle that had not been periodically inspected, and using a disqualified driver.

The company shut down shortly after the crash. Contact information for the owner to offer comment cannot be found.