OKLAHOMA CITY - Four people were killed and five others were seriously injured, when a semi plowed across a median and slammed into a bus of college students.
It happened in September of 2014.
Tuesday, an official report states the truck driver was high on synthetic marijuana.
A new report released by the NTSB said the trucking industry needs better tools to detect impaired drivers.
In Oklahoma, one trucking school said they agree.
They, themselves, screen any applicant, before they ever get behind the wheel.
Four young lives taken and, now a year later, more information is released.
"When you have an accident of this magnitude, where you have serious injury or death involved, like in this case, it's our practice, our policy that we do - blood test or breath test," said Cpt. Paul Timmons with Oklahoma Highway Patrol.
Today's official NTSB report stated the driver of the semi that hit the bus was high on synthetic marijuana.
"He was tested within two hours of when the bus crash occurred that same night," Timmons said.
Agencies are now urging the trucking industry to do more to detect drivers that could be under the influence.
In a press release, a spokesperson for the NTSB said "motor carriers need to know about this emerging class of drugs, and they need better tools to detect driver impairment."
"It happens out there. There's guys out there that still do it. It's just that companies need to get more stringent on their drug tests," said David Druschel, director of training at American Truck Training in Oklahoma.
Druschel has more than 45 years in the trucking industry, teaching the drivers who go on to work for bigger companies.
"I think the companies should increase their tests," Druschel said, "If they're testing 100 drivers a month, bring it up to 200-300 a month."
The truck school he works for even drug tests applicants.
"If the companies crack down more, I believe that people would take them more serious," Druschel said.
It's a matter related to life and death, while driving on highways.
"It's the one bad apple that has brought the eyes on the whole trucking industry," Druschel said.
The report also pointed out there should be more done to pass legislation that all buses and commercial vehicles should have seat belts in them.