One man died and another was critically injured early Thursday in a three-vehicle wreck at Sixth and Kentucky streets.

Police said 44-year-old Wade Collins died when the minivan he was driving crossed the center line on eastbound Sixth Street, struck an oncoming pickup truck and knocked it into another westbound pickup truck in the adjoining lane. The wreck happened at 6:38 a.m., and traffic was backed up until mid-morning as police rerouted vehicles around the scene.

Hazardous-materials crews from Lawrence-Douglas County Fire & Medical responded after learning that the first pickup truck hit was carrying low-grade radioactive materials for medical use. The materials were from Cardinal Health Inc., a company with an office in the Kansas City, Mo., area, but a company manager declined comment Thursday.

Two large metal boxes labeled “radioactive” could be seen on the ground behind the pickup truck as officers worked the accident scene.

But Fire & Medical Chief Mark Bradford said none of the radioactive material being carried in the truck spilled outside its containers. The amount of radioactivity was so low, he said, that federal regulations didn’t require the pickup truck to be marked with special placards.

Medical-grade radioactive material “is transported just like this was,” Bradford said. “It’s on airplanes. It’s on a variety of things.”

Bradford said that if the containers had leaked, hazmat crews likely would have tried to contain the leakage by putting the containers inside a metal drum and sealing it. Hazmat crews are trained to contain and mitigate spills, but not to clean them up, he said.

Collins was pronounced dead at Lawrence Memorial Hospital. His passenger, John Knackstedt Jr., 36, was flown by air ambulance to University of Kansas Hospital in Kansas City, Kan., but a condition update was not available Thursday evening.

The driver of the pickup carrying radioactive material was identified as Kenneth Searzy, 62, of Kansas City, Mo. He and a passenger, John Sewell, 62, Lee’s Summit, Mo., were taken to Lawrence Memorial Hospital.

Searzy was treated and released. Sewell was listed in fair condition Thursday evening.

The driver of the second pickup truck, Jeff Noll, 40, of Valley Falls, was not injured.

The circumstances that led to the wreck remained under investigation Thursday.

A member of Collins’ family, reached by telephone Thursday evening, said she thought Collins was on his way to work. She declined to talk more about him except to say that he would “do anything” for other people.

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It was the second fatal wreck in Lawrence this year. The first happened Nov. 25 at 19th and Massachusetts streets. Wesley Norwood, 77, died at Lawrence Memorial Hospital two days after that wreck.

Doug Billings, lead nuclear medical technologist for Lawrence Memorial Hospital, said the radioactive materials in the pickup weren’t headed for LMH but that the hospital regularly used the company to deliver materials used for medical imaging. The materials, which look like a clear solution, often are carried in syringes encased in lead sheaths, he said.

“Part of the reason it’s safe to transport is that most of it is low energy,” he said.

— 6News reporter Brooke Wehner contributed information to this article.