PHOENIX — Three people were injured after three tractor-trailers were involved in an accident in northern Arizona Saturday night, authorities said.

The crash happened around 10 p.m. at milepost 178 on eastbound Interstate 40, approximately 20 miles west of Flagstaff, the Ponderosa Fire Department said in a Facebook post.

The three people involved required extrication, with one person needing airlift transportation and the other two transported by ground, authorities said.

Eastbound I-40 was down to one lane, with traffic moving slowly, as of Sunday morning around 9 a.m.

The cause of the crash and conditions of the injured weren’t immediately known.

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