UPDATED: 3/6/16 9:26 p.m.

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DENTON (CBSDFW.COM) — I-35 north near Denton and Sanger was shut down after a semi-truck crash, causing significant delays, officials say.

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Denton police responded to the crash just after 12 p.m. Sunday on I-35 north at the 475B exit, according to a statement from the Denton Police Department. Witnesses said the semi-truck appeared to be swaying side-to-side as it was driving northbound. The truck was reportedly taking the 475B exit when it hit the guardrail, causing it to flip onto its side. The driver was airlifted from the scene. Police said just after 5:30 p.m. that the lanes were about to reopen.

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(Photo: Denton Police Department)

(Photo: Denton Police Department)

Police said the 26-year-old semi-truck driver was able to get out of the cab but then collapsed and lost consciousness. CareFlight airlifted him from the crash site but had to land in Addison on its way to the Medical Center of Plano “due to deteriorating flight conditions,” according to the statement. The driver was then taken by ambulance to the hospital. His condition is unknown.

Police said the semi-truck was the only vehicle involved in the crash and that officers were investigating the cause.

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